<algorithm>是C++标准程序库中的一个头文件，定义了C++ STL标准中的基础性的算法(均为函数模板)。<algorithm>定义了设计用于元素范围的函数集合。任何对象序列的范围可以通过迭代器或指针访问。
std::adjacent_find：在序列中查找第一对相邻且值相等的元素；
std::find: 对一个输入序列，查找第一个等于给定值的元素；
std::find_end: 查找有B定义的序列在A序列中最后一次出现的位置(B可能是A的子序列)；
std::find_first_of:查找A序列中第一个与序列B中任一元素值相等的元素位置；
std::find_if: 在序列中返回满足谓词(给定的条件)的第一个元素；
std::find_if_not:在序列中返回不满足谓词的第一个元素；
std::all_of: 如果序列中所有元素均满足给定的条件，则返回true；
std::any_of: 如果序列中存在元素满足给定的条件，则返回true；
std::none_of: 如果序列中所有元素均不满足给定的条件，则返回true；
std::binary_search:对一个升序序列做二分搜索，判断序列中是否有与给定值相等的元素；
std::search: 在序列A中，搜索B首次出现的位置(B可能是A的子序列)；
std::search_n: 在给定序列中，搜索给定值连续出现n次的位置；
std::copy: 将一个序列中的元素拷贝到新的位置；
std::copy_backward:把一个序列复制到另一个序列，按照由尾到头顺序依次复制元素；
std::copy_if: 将一个序列中满足给定条件的元素拷贝到新的位置；
std::copy_n: 将一个序列中的前n个元素拷贝到新的位置；
std::count: 返回序列中等于给定值元素的个数；
std::count_if: 返回序列中满足给定条件的元素的个数；
std::equal: 比较两个序列的对应元素是否相等；
std::equal_range:在已排序的序列中，查找元素等于给定值组成的子范围；
std::lower_bound:在升序的序列中，查找第一个不小于给定值的元素；
std::upper_bound:在已排序的序列中，查找第一个大于给定值的元素；
std::fill: 用给定值填充序列中的每个元素；
std::fill_n: 用给定值填充序列中的n个元素；
std::for_each: 将指定函数应用于范围内的每一个元素；
std::generate: 对序列中的每个元素，用依次调用函数gen的返回值赋值；
std::generate_n:对序列中的n个元素，用依次调用指定函数gen的返回值赋值；
std::includes: 判断第二个已排序的序列是否全部都出现在第一个已排序的序列中；
std::inplace_merge:对两个升序的序列执行原地合并，合并后的序列仍保持升序；
std::merge: 对两个升序的序列合并，结果序列保持升序；
std::is_heap: 判断序列是否为二叉堆；
std::is_heap_until:查找第一个不是堆顺序的元素；
std::make_heap: 对于一个序列，构造一个二叉堆；
std::pop_heap: 堆的根节点被移除，堆的元素数目减1并保持堆性质；
std::push_heap: 向堆中增加一个新元素，新元素最初保存在last-1位置；
std::sort_heap: 对一个堆，执行原地堆排序，得到一个升序结果；
std::is_partitioned：判断序列是否按指定谓词划分过；
std::partition: 对序列重排，使得满足谓词的元素位于最前；
std::partition_copy:输入序列中，满足谓词的元素复制到result_true，其它元素复制到result_false；
std::partition_point:输入序列已经是partition，折半查找到分界点；
std::stable_partiton:对序列重排，使得满足谓词的元素在前，不满足谓词的元素在后，且两组元素内部的相对顺序不变；
std::is_permutation:判断两个序列是否为同一元素的两个排列；
std::next_permutation:n个元素有n!中排列。这些排列中，规定升序序列为最小排列，降序序列为最大的排列，任意两个排列按照字典序分出大小。该函数返回当前序列作为一个排列按字典序的下一个排列；
std::prev_permutation:返回当前序列作为一个排列按字典序的上一个排列；
std::is_sorted: 判断序列是否为升序；
std::is_sorted_until:查找序列中第一个未排序的元素；
std::nth_element:对序列重排，使得指定的位置出现的元素就是有序情况下应该在该位置出现的那个元素，且在指定位置之前的元素都小于指定位置元素，在指定位置之后的元素都大于指定位置元素；
std::partial_sort:对序列进行部分排序；
std::partial_sort_copy:拷贝部分排序的序列；
std::sort: 对序列进行排序；
std::stable_sort:对序列进行稳定排序；
std::iter_swap: 交换两个迭代器指向的元素；
std::swap: 交换两个对象，优先使用移动语义；
std::swap_ranges:交换两个序列中对应元素；
std::lexicographical_compare：对两个序列做字典比较，如果第一个序列在字典序下小于第二个序列，则返回true；
std::min: 返回两个值中的最小值；
std::min_element：返回序列中的最小值；
std::max: 返回两个值中的最大值；
std::max_element:返回序列中的最大值；
std::minmax: 返回由最小值与最大值构成的std::pair；
std::minmax_element:返回由序列中最小元素与最大元素构成的std::pair；
std::mismatch: 比较两个序列的对应元素，返回用std::pair表示的第一处不匹配在两个序列的位置；
std::move: 把输入序列中的逐个元素移动到结果序列；注意与 http://blog.csdn.net/fengbingchun/article/details/52558914 中的不同；
std::move_backward:把输入序列中的逐个元素自尾到头移动到结果序列；
std::shuffle: 使用均匀随机数生成器，随机打乱指定范围中的元素的位置；
std::random_shuffle:n个元素有!n个排列，该函数给出随机选择的一个排列；
std::remove: 删除序列中等于给定值的所有元素；
std::remove_if: 删除序列中满足给定谓词的元素；
std::remove_copy:把一个序列中不等于给定值的元素复制到另一个序列中；
std::remove_copy_if:把一个序列中不满足给定谓词的元素复制到另一个序列中；
std::replace: 把序列中等于给定值的元素替换为新值；
std::replace_if:把序列中满足给定谓词的元素替换为新值；
std::replace_copy:拷贝序列，对于等于老值的元素复制时使用新值；
std::replace_copy_if:拷贝序列，对于满足给定谓词的元素复制时使用新值；
std::reverse: 把序列中的元素逆序；
std::reverse_copy:拷贝序列的逆序到另一个序列中；
std::rotate: 等效于循环左移序列，使得迭代器middle所指的元素成为首元素；
std::rotate_copy:等效于循环左移序列并拷贝到新的序列中，使得迭代器middle所指的元素成为首元素；
std::set_difference:两个升序序列之差；
std::set_intersection:两个升序序列的交；
std::set_symmetric_difference:两个升序序列的对称差；
std::set_union: 两个升序序列的并；
std::transform: 对序列中的每一个元素，执行一元操作，结果写入另一序列中；或对两个序列中对应的每一对元素，执行二元操作，结果写入另一序列中；
std::unique: 对序列中一群连续的相等的元素，仅保留第一个元素；
std::unique_copy:把一个序列中的元素拷贝到另一个序列，对于一群连续的相等的元素，仅拷贝第一个元素。
1 #include "algorithm.hpp" 2 #include <algorithm> 3 #include <iostream> 4 #include <vector> 5 #include <cctype> 6 #include <array> 7 #include <ctime> 8 #include <cstdlib> 9 #include <string> 10 #include <random> 11 #include <chrono> 12 13 // reference: http://www.cplusplus.com/reference/algorithm/ 14 15 namespace algorithm_ { 16 17 /////////////////////////////////////// 18 static bool myfunction(int i, int j) { return (i == j); } 19 static bool comp_case_insensitive(char c1, char c2) { return (std::tolower(c1) == std::tolower(c2)); } 20 static bool IsOdd(int i) { return ((i % 2) == 1); } 21 22 int test_algorithm_find() 23 { 24 { 25 int myints[] = { 5, 20, 5, 30, 30, 20, 10, 10, 20 }; 26 std::vector<int> myvector(myints, myints + 8); 27 std::vector<int>::iterator it; 28 29 // using default comparison: 30 it = std::adjacent_find(myvector.begin(), myvector.end()); 31 32 if (it != myvector.end()) 33 std::cout << "the first pair of repeated elements are: " << *it << '\n'; // 30 34 35 //using predicate comparison: 36 it = std::adjacent_find(++it, myvector.end(), myfunction); 37 38 if (it != myvector.end()) 39 std::cout << "the second pair of repeated elements are: " << *it << '\n'; // 10 40 } 41 42 { 43 // using std::find with array and pointer: 44 int myints[] = { 10, 20, 30, 40 }; 45 int * p; 46 47 p = std::find(myints, myints + 4, 30); 48 if (p != myints + 4) 49 std::cout << "Element found in myints: " << *p << '\n'; // 30 50 else 51 std::cout << "Element not found in myints\n"; 52 53 // using std::find with vector and iterator: 54 std::vector<int> myvector(myints, myints + 4); 55 std::vector<int>::iterator it; 56 57 it = std::find(myvector.begin(), myvector.end(), 30); 58 if (it != myvector.end()) 59 std::cout << "Element found in myvector: " << *it << '\n'; // 30 60 else 61 std::cout << "Element not found in myvector\n"; 62 } 63 64 { 65 int myints[] = { 1, 2, 3, 4, 5, 1, 2, 3, 4, 5 }; 66 std::vector<int> haystack(myints, myints + 10); 67 68 int needle1[] = { 1, 2, 3 }; 69 70 // using default comparison: 71 std::vector<int>::iterator it; 72 it = std::find_end(haystack.begin(), haystack.end(), needle1, needle1 + 3); 73 74 if (it != haystack.end()) 75 std::cout << "needle1 last found at position " << (it - haystack.begin()) << '\n'; // 5 76 77 int needle2[] = { 4, 5, 1 }; 78 79 // using predicate comparison: 80 it = std::find_end(haystack.begin(), haystack.end(), needle2, needle2 + 3, myfunction); 81 82 if (it != haystack.end()) 83 std::cout << "needle2 last found at position " << (it - haystack.begin()) << '\n'; // 3 84 } 85 86 { 87 int mychars[] = { 'a', 'b', 'c', 'A', 'B', 'C' }; 88 std::vector<char> haystack(mychars, mychars + 6); 89 std::vector<char>::iterator it; 90 91 int needle[] = { 'A', 'B', 'C' }; 92 93 // using default comparison: 94 it = find_first_of(haystack.begin(), haystack.end(), needle, needle + 3); 95 96 if (it != haystack.end()) 97 std::cout << "The first match is: " << *it << '\n'; // A 98 99 // using predicate comparison: 100 it = find_first_of(haystack.begin(), haystack.end(), needle, needle + 3, comp_case_insensitive); 101 102 if (it != haystack.end()) 103 std::cout << "The first match is: " << *it << '\n'; // a 104 } 105 106 { 107 std::vector<int> myvector; 108 109 myvector.push_back(10); 110 myvector.push_back(25); 111 myvector.push_back(40); 112 myvector.push_back(55); 113 114 std::vector<int>::iterator it = std::find_if(myvector.begin(), myvector.end(), IsOdd); 115 std::cout << "The first odd value is " << *it << '\n'; // 25 116 } 117 118 { 119 std::array<int, 5> foo = { 1, 2, 3, 4, 5 }; 120 121 std::array<int, 5>::iterator it = std::find_if_not(foo.begin(), foo.end(), [](int i){return i % 2; }); 122 std::cout << "The first even value is " << *it << '\n'; // 2 123 } 124 125 return 0; 126 } 127 128 //////////////////////////////////////////// 129 int test_algorithm_all_of() 130 { 131 { 132 std::array<int, 8> foo = { 3, 5, 7, 11, 13, 17, 19, 23 }; 133 134 if (std::all_of(foo.begin(), foo.end(), [](int i){return i % 2; })) 135 std::cout << "All the elements are odd numbers.\n"; // All the elements are odd numbers 136 } 137 138 { 139 std::array<int, 7> foo = { 0, 1, -1, 3, -3, 5, -5 }; 140 141 if (std::any_of(foo.begin(), foo.end(), [](int i){return i<0; })) 142 std::cout << "There are negative elements in the range.\n"; // There are negative elements in the range 143 } 144 145 { 146 std::array<int, 8> foo = { 1, 2, 4, 8, 16, 32, 64, 128 }; 147 148 if (std::none_of(foo.begin(), foo.end(), [](int i){return i<0; })) 149 std::cout << "There are no negative elements in the range.\n"; // There are no negative elements in the range 150 } 151 152 return 0; 153 } 154 155 //////////////////////////////////////////////// 156 static bool myfunction2(int i, int j) { return (i<j); } 157 static bool mypredicate(int i, int j) { return (i == j); } 158 159 int test_algorithm_search() 160 { 161 { 162 int myints[] = { 1, 2, 3, 4, 5, 4, 3, 2, 1 }; 163 std::vector<int> v(myints, myints + 9); 164 165 // using default comparison: 166 std::sort(v.begin(), v.end()); 167 168 std::cout << "looking for a 3... "; 169 if (std::binary_search(v.begin(), v.end(), 3)) std::cout << "found!\n"; // found! 170 else std::cout << "not found.\n"; 171 172 // using myfunction as comp: 173 std::sort(v.begin(), v.end(), myfunction2); 174 175 std::cout << "looking for a 6... "; 176 if (std::binary_search(v.begin(), v.end(), 6, myfunction2)) std::cout << "found!\n"; 177 else std::cout << "not found.\n"; // not found. 178 } 179 180 { 181 std::vector<int> haystack; 182 183 // set some values: haystack: 10 20 30 40 50 60 70 80 90 184 for (int i = 1; i<10; i++) haystack.push_back(i * 10); 185 186 // using default comparison: 187 int needle1[] = { 40, 50, 60, 70 }; 188 std::vector<int>::iterator it; 189 it = std::search(haystack.begin(), haystack.end(), needle1, needle1 + 4); 190 191 if (it != haystack.end()) 192 std::cout << "needle1 found at position " << (it - haystack.begin()) << '\n'; // 3 193 else 194 std::cout << "needle1 not found\n"; 195 196 // using predicate comparison: 197 int needle2[] = { 20, 30, 50 }; 198 it = std::search(haystack.begin(), haystack.end(), needle2, needle2 + 3, mypredicate); 199 200 if (it != haystack.end()) 201 std::cout << "needle2 found at position " << (it - haystack.begin()) << '\n'; 202 else 203 std::cout << "needle2 not found\n"; // needle2 not found 204 } 205 206 { 207 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; 208 std::vector<int> myvector(myints, myints + 8); 209 210 std::vector<int>::iterator it; 211 212 // using default comparison: 213 it = std::search_n(myvector.begin(), myvector.end(), 2, 30); 214 215 if (it != myvector.end()) 216 std::cout << "two 30s found at position " << (it - myvector.begin()) << '\n'; // 2 217 else 218 std::cout << "match not found\n"; 219 220 // using predicate comparison: 221 it = std::search_n(myvector.begin(), myvector.end(), 2, 10, mypredicate); 222 223 if (it != myvector.end()) 224 std::cout << "two 10s found at position " << int(it - myvector.begin()) << '\n'; // 5 225 else 226 std::cout << "match not found\n"; 227 } 228 229 return 0; 230 } 231 232 ////////////////////////////////////////////// 233 int test_algorithm_copy() 234 { 235 { 236 int myints[] = { 10, 20, 30, 40, 50, 60, 70 }; 237 std::vector<int> myvector(7); 238 239 std::copy(myints, myints + 7, myvector.begin()); 240 241 std::cout << "myvector contains:"; 242 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 243 std::cout << ' ' << *it; // 10 20 30 40 50 60 70 244 245 std::cout << '\n'; 246 } 247 248 { 249 std::vector<int> myvector; 250 251 // set some values: 252 for (int i = 1; i <= 5; i++) 253 myvector.push_back(i * 10); // myvector: 10 20 30 40 50 254 255 myvector.resize(myvector.size() + 3); // allocate space for 3 more elements 256 257 std::copy_backward(myvector.begin(), myvector.begin() + 5, myvector.end()); 258 259 std::cout << "myvector contains:"; 260 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 261 std::cout << ' ' << *it; // 10 20 30 10 20 30 40 50 262 std::cout << '\n'; 263 } 264 265 { 266 std::vector<int> foo = { 25, 15, 5, -5, -15 }; 267 std::vector<int> bar(foo.size()); 268 269 // copy only positive numbers: 270 auto it = std::copy_if(foo.begin(), foo.end(), bar.begin(), [](int i){return !(i<0); }); 271 bar.resize(std::distance(bar.begin(), it)); // shrink container to new size 272 273 std::cout << "bar contains:"; 274 for (int& x : bar) std::cout << ' ' << x; // 25 15 5 275 std::cout << '\n'; 276 } 277 278 { 279 int myints[] = { 10, 20, 30, 40, 50, 60, 70 }; 280 std::vector<int> myvector; 281 282 myvector.resize(7); // allocate space for 7 elements 283 284 std::copy_n(myints, 7, myvector.begin()); 285 286 std::cout << "myvector contains:"; 287 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 288 std::cout << ' ' << *it; // 10 20 30 40 50 60 70 289 290 std::cout << '\n'; 291 } 292 293 return 0; 294 } 295 296 /////////////////////////////////////////////// 297 int test_algorithm_count() 298 { 299 { 300 // counting elements in array: 301 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; // 8 elements 302 int mycount = std::count(myints, myints + 8, 10); 303 std::cout << "10 appears " << mycount << " times.\n"; // 3 304 305 // counting elements in container: 306 std::vector<int> myvector(myints, myints + 8); 307 mycount = std::count(myvector.begin(), myvector.end(), 20); 308 std::cout << "20 appears " << mycount << " times.\n"; // 3 309 } 310 311 { 312 std::vector<int> myvector; 313 for (int i = 1; i<10; i++) myvector.push_back(i); // myvector: 1 2 3 4 5 6 7 8 9 314 315 int mycount = count_if(myvector.begin(), myvector.end(), IsOdd); 316 std::cout << "myvector contains " << mycount << " odd values.\n"; // 5 317 } 318 319 return 0; 320 } 321 322 ////////////////////////////////////////// 323 static bool mygreater(int i, int j) { return (i>j); } 324 325 int test_algorithm_equal() 326 { 327 { 328 int myints[] = { 20, 40, 60, 80, 100 }; // myints: 20 40 60 80 100 329 std::vector<int>myvector(myints, myints + 5); // myvector: 20 40 60 80 100 330 331 // using default comparison: 332 if (std::equal(myvector.begin(), myvector.end(), myints)) 333 std::cout << "The contents of both sequences are equal.\n"; // equal 334 else 335 std::cout << "The contents of both sequences differ.\n"; 336 337 myvector[3] = 81; // myvector: 20 40 60 81 100 338 339 // using predicate comparison: 340 if (std::equal(myvector.begin(), myvector.end(), myints, mypredicate)) 341 std::cout << "The contents of both sequences are equal.\n"; 342 else 343 std::cout << "The contents of both sequences differ.\n"; // differ 344 } 345 346 { 347 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; 348 std::vector<int> v(myints, myints + 8); // 10 20 30 30 20 10 10 20 349 std::pair<std::vector<int>::iterator, std::vector<int>::iterator> bounds; 350 351 // using default comparison: 352 std::sort(v.begin(), v.end()); // 10 10 10 20 20 20 30 30 353 bounds = std::equal_range(v.begin(), v.end(), 20); // ^ ^ 354 355 std::cout << "bounds at positions " << (bounds.first - v.begin()); // 3 356 std::cout << " and " << (bounds.second - v.begin()) << '\n'; // 6 357 358 // using "mygreater" as comp: 359 std::sort(v.begin(), v.end(), mygreater); // 30 30 20 20 20 10 10 10 360 bounds = std::equal_range(v.begin(), v.end(), 20, mygreater); // ^ ^ 361 362 std::cout << "bounds at positions " << (bounds.first - v.begin()); // 2 363 std::cout << " and " << (bounds.second - v.begin()) << '\n'; // 5 364 } 365 366 { 367 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; 368 std::vector<int> v(myints, myints + 8); // 10 20 30 30 20 10 10 20 369 370 std::sort(v.begin(), v.end()); // 10 10 10 20 20 20 30 30 371 372 std::vector<int>::iterator low, up; 373 low = std::lower_bound(v.begin(), v.end(), 20); 374 up = std::upper_bound(v.begin(), v.end(), 20); 375 376 std::cout << "lower_bound at position " << (low - v.begin()) << '\n'; // 3 377 std::cout << "upper_bound at position " << (up - v.begin()) << '\n'; // 6 378 } 379 380 return 0; 381 } 382 383 ////////////////////////////////////////// 384 int test_algorithm_fill() 385 { 386 { 387 std::vector<int> myvector(8); // myvector: 0 0 0 0 0 0 0 0 388 389 std::fill(myvector.begin(), myvector.begin() + 4, 5); // myvector: 5 5 5 5 0 0 0 0 390 std::fill(myvector.begin() + 3, myvector.end() - 2, 8); // myvector: 5 5 5 8 8 8 0 0 391 392 std::cout << "myvector contains:"; 393 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 394 std::cout << ' ' << *it; // 5 5 5 8 8 8 0 0 395 std::cout << '\n'; 396 } 397 398 { 399 std::vector<int> myvector(8, 10); // myvector: 10 10 10 10 10 10 10 10 400 401 std::fill_n(myvector.begin(), 4, 20); // myvector: 20 20 20 20 10 10 10 10 402 std::fill_n(myvector.begin() + 3, 3, 33); // myvector: 20 20 20 33 33 33 10 10 403 404 std::cout << "myvector contains:"; 405 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 406 std::cout << ' ' << *it; // 20 20 20 33 33 33 10 10 407 std::cout << '\n'; 408 } 409 410 return 0; 411 } 412 413 /////////////////////////////////////////// 414 void myfunction3(int i) { // function: 415 std::cout << ' ' << i; 416 } 417 418 struct myclass { // function object type: 419 void operator() (int i) { std::cout << ' ' << i; } 420 } myobject; 421 422 int test_algorithm_for_each() 423 { 424 std::vector<int> myvector; 425 myvector.push_back(10); 426 myvector.push_back(20); 427 myvector.push_back(30); 428 429 std::cout << "myvector contains:"; 430 for_each(myvector.begin(), myvector.end(), myfunction3); // 10 20 30 431 std::cout << '\n'; 432 433 // or: 434 std::cout << "myvector contains:"; 435 for_each(myvector.begin(), myvector.end(), myobject); // 10 20 30 436 std::cout << '\n'; 437 438 return 0; 439 } 440 441 //////////////////////////////////////////////// 442 // function generator: 443 int RandomNumber() { return (std::rand() % 100); } 444 445 // class generator: 446 struct c_unique { 447 int current; 448 c_unique() { current = 0; } 449 int operator()() { return ++current; } 450 } UniqueNumber; 451 452 int current = 0; 453 int UniqueNumber2() { return ++current; } 454 455 int test_algorithm_generate() 456 { 457 { 458 std::srand(unsigned(std::time(0))); 459 460 std::vector<int> myvector(8); 461 462 std::generate(myvector.begin(), myvector.end(), RandomNumber); 463 464 std::cout << "myvector contains:"; 465 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 466 std::cout << ' ' << *it; 467 std::cout << '\n'; 468 469 std::generate(myvector.begin(), myvector.end(), UniqueNumber); 470 471 std::cout << "myvector contains:"; 472 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 473 std::cout << ' ' << *it; // 1 2 3 4 5 6 7 8 474 std::cout << '\n'; 475 } 476 477 { 478 int myarray[9]; 479 480 std::generate_n(myarray, 9, UniqueNumber2); 481 482 std::cout << "myarray contains:"; 483 for (int i = 0; i<9; ++i) 484 std::cout << ' ' << myarray[i]; // 1 2 3 4 5 6 7 8 9 485 std::cout << '\n'; 486 } 487 488 return 0; 489 } 490 491 //////////////////////////////////////////////// 492 int test_algorithm_includes() 493 { 494 int container[] = { 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 }; 495 int continent[] = { 40, 30, 20, 10 }; 496 497 std::sort(container, container + 10); 498 std::sort(continent, continent + 4); 499 500 // using default comparison: 501 if (std::includes(container, container + 10, continent, continent + 4)) 502 std::cout << "container includes continent!\n"; // container includes continent 503 504 // using myfunction as comp: 505 if (std::includes(container, container + 10, continent, continent + 4, myfunction2)) 506 std::cout << "container includes continent!\n"; // container includes continent 507 508 return 0; 509 } 510 511 /////////////////////////////////////////////////////////// 512 int test_algorithm_merge() 513 { 514 { 515 int first[] = { 5, 10, 15, 20, 25 }; 516 int second[] = { 50, 40, 30, 20, 10 }; 517 std::vector<int> v(10); 518 std::vector<int>::iterator it; 519 520 std::sort(first, first + 5); 521 std::sort(second, second + 5); 522 523 it = std::copy(first, first + 5, v.begin()); 524 std::copy(second, second + 5, it); 525 526 std::inplace_merge(v.begin(), v.begin() + 5, v.end()); 527 528 std::cout << "The resulting vector contains:"; 529 for (it = v.begin(); it != v.end(); ++it) 530 std::cout << ' ' << *it; // 5 10 10 15 20 20 25 30 40 50 531 std::cout << '\n'; 532 } 533 534 { 535 int first[] = { 5, 10, 15, 20, 25 }; 536 int second[] = { 50, 40, 30, 20, 10 }; 537 std::vector<int> v(10); 538 539 std::sort(first, first + 5); 540 std::sort(second, second + 5); 541 std::merge(first, first + 5, second, second + 5, v.begin()); 542 543 std::cout << "The resulting vector contains:"; 544 for (std::vector<int>::iterator it = v.begin(); it != v.end(); ++it) 545 std::cout << ' ' << *it; // 5 10 10 15 20 20 25 30 40 50 546 std::cout << '\n'; 547 } 548 549 return 0; 550 } 551 552 //////////////////////////////////////// 553 int test_algorithm_heap() 554 { 555 { 556 std::vector<int> foo{ 9, 5, 2, 6, 4, 1, 3, 8, 7 }; 557 558 if (!std::is_heap(foo.begin(), foo.end())) 559 std::make_heap(foo.begin(), foo.end()); 560 561 std::cout << "Popping out elements:"; 562 while (!foo.empty()) { 563 std::pop_heap(foo.begin(), foo.end()); // moves largest element to back 564 std::cout << ' ' << foo.back(); // prints back // 9 8 7 6 5 4 3 2 1 565 foo.pop_back(); // pops element out of container 566 } 567 std::cout << '\n'; 568 } 569 570 { 571 std::vector<int> foo{ 2, 6, 9, 3, 8, 4, 5, 1, 7 }; 572 573 std::sort(foo.begin(), foo.end()); 574 std::reverse(foo.begin(), foo.end()); 575 576 auto last = std::is_heap_until(foo.begin(), foo.end()); 577 578 std::cout << "The " << (last - foo.begin()) << " first elements are a valid heap:"; // 9 579 for (auto it = foo.begin(); it != last; ++it) 580 std::cout << ' ' << *it; // 9 8 7 6 5 4 3 2 1 581 std::cout << '\n'; 582 } 583 584 { 585 int myints[] = { 10, 20, 30, 5, 15 }; 586 std::vector<int> v(myints, myints + 5); 587 588 std::make_heap(v.begin(), v.end()); 589 std::cout << "initial max heap : " << v.front() << '\n'; // 30 590 591 std::pop_heap(v.begin(), v.end()); v.pop_back(); 592 std::cout << "max heap after pop : " << v.front() << '\n'; // 20 593 594 v.push_back(99); std::push_heap(v.begin(), v.end()); 595 std::cout << "max heap after push: " << v.front() << '\n'; // 99 596 597 std::sort_heap(v.begin(), v.end()); 598 599 std::cout << "final sorted range :"; 600 for (unsigned i = 0; i<v.size(); i++) 601 std::cout << ' ' << v[i]; // 5 10 15 20 99 602 603 std::cout << '\n'; 604 } 605 606 return 0; 607 } 608 609 //////////////////////////////////////////// 610 int test_algorithm_partition() 611 { 612 { 613 std::array<int, 7> foo{ 1, 2, 3, 4, 5, 6, 7 }; 614 615 // print contents: 616 std::cout << "foo:"; for (int& x : foo) std::cout << ' ' << x; 617 if (std::is_partitioned(foo.begin(), foo.end(), IsOdd)) 618 std::cout << " (partitioned)\n"; 619 else 620 std::cout << " (not partitioned)\n"; // not partitioned 621 622 // partition array: 623 std::partition(foo.begin(), foo.end(), IsOdd); 624 625 // print contents again: 626 std::cout << "foo:"; for (int& x : foo) std::cout << ' ' << x; // 1 7 3 5 4 6 2 627 if (std::is_partitioned(foo.begin(), foo.end(), IsOdd)) 628 std::cout << " (partitioned)\n"; // partitioned 629 else 630 std::cout << " (not partitioned)\n"; 631 } 632 633 { 634 std::vector<int> myvector; 635 636 // set some values: 637 for (int i = 1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 638 639 std::vector<int>::iterator bound; 640 bound = std::partition(myvector.begin(), myvector.end(), IsOdd); 641 642 // print out content: 643 std::cout << "odd elements:"; 644 for (std::vector<int>::iterator it = myvector.begin(); it != bound; ++it) 645 std::cout << ' ' << *it; // 1 9 3 7 5 646 std::cout << '\n'; 647 648 std::cout << "even elements:"; 649 for (std::vector<int>::iterator it = bound; it != myvector.end(); ++it) 650 std::cout << ' ' << *it; // 6 4 8 2 651 std::cout << '\n'; 652 } 653 654 { 655 std::vector<int> foo{ 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 656 std::vector<int> odd, even; 657 658 // resize vectors to proper size: 659 unsigned n = std::count_if(foo.begin(), foo.end(), IsOdd); 660 odd.resize(n); even.resize(foo.size() - n); 661 662 // partition: 663 std::partition_copy(foo.begin(), foo.end(), odd.begin(), even.begin(), IsOdd); 664 665 // print contents: 666 std::cout << "odd: "; for (int& x : odd) std::cout << ' ' << x; std::cout << '\n'; // 1 3 5 7 9 667 std::cout << "even: "; for (int& x : even) std::cout << ' ' << x; std::cout << '\n'; // 2 4 6 8 668 } 669 670 { 671 std::vector<int> foo{ 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 672 std::vector<int> odd; 673 674 std::partition(foo.begin(), foo.end(), IsOdd); 675 676 auto it = std::partition_point(foo.begin(), foo.end(), IsOdd); 677 odd.assign(foo.begin(), it); 678 679 // print contents of odd: 680 std::cout << "odd:"; 681 for (int& x : odd) std::cout << ' ' << x; // 1 9 3 7 5 682 std::cout << '\n'; 683 } 684 685 { 686 std::vector<int> myvector; 687 688 // set some values: 689 for (int i = 1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 690 691 std::vector<int>::iterator bound; 692 bound = std::stable_partition(myvector.begin(), myvector.end(), IsOdd); 693 694 // print out content: 695 std::cout << "odd elements:"; 696 for (std::vector<int>::iterator it = myvector.begin(); it != bound; ++it) 697 std::cout << ' ' << *it; // 1 3 5 7 9 698 std::cout << '\n'; 699 700 std::cout << "even elements:"; 701 for (std::vector<int>::iterator it = bound; it != myvector.end(); ++it) 702 std::cout << ' ' << *it; // 2 4 6 8 703 std::cout << '\n'; 704 } 705 706 return 0; 707 } 708 709 ////////////////////////////////////// 710 int test_algorithm_permutation() 711 { 712 { 713 std::array<int, 5> foo = { 1, 2, 3, 4, 5 }; 714 std::array<int, 5> bar = { 3, 1, 4, 5, 2 }; 715 716 if (std::is_permutation(foo.begin(), foo.end(), bar.begin())) 717 std::cout << "foo and bar contain the same elements.\n"; // foo and bar contain the same elements 718 } 719 720 { 721 int myints[] = { 1, 2, 3 }; 722 723 std::sort(myints, myints + 3); 724 725 std::cout << "The 3! possible permutations with 3 elements:\n"; 726 do { 727 std::cout << myints[0] << ' ' << myints[1] << ' ' << myints[2] << '\n'; 728 } while (std::next_permutation(myints, myints + 3)); 729 730 std::cout << "After loop: " << myints[0] << ' ' << myints[1] << ' ' << myints[2] << '\n'; // 1 2 3 731 } 732 733 { 734 int myints[] = { 1, 2, 3 }; 735 736 std::sort(myints, myints + 3); 737 std::reverse(myints, myints + 3); 738 739 std::cout << "The 3! possible permutations with 3 elements:\n"; 740 do { 741 std::cout << myints[0] << ' ' << myints[1] << ' ' << myints[2] << '\n'; 742 } while (std::prev_permutation(myints, myints + 3)); 743 744 std::cout << "After loop: " << myints[0] << ' ' << myints[1] << ' ' << myints[2] << '\n'; // 3 2 1 745 } 746 747 return 0; 748 } 749 750 ///////////////////////////////////////////// 751 struct myclass2 { 752 bool operator() (int i, int j) { return (i<j); } 753 } myobject2; 754 755 bool compare_as_ints(double i, double j) { return (int(i)<int(j)); } 756 757 int test_algorithm_sort() 758 { 759 { 760 std::array<int, 4> foo{ 2, 4, 1, 3 }; 761 762 do { 763 // try a new permutation: 764 std::prev_permutation(foo.begin(), foo.end()); 765 766 // print range: 767 std::cout << "foo:"; 768 for (int& x : foo) std::cout << ' ' << x; 769 std::cout << '\n'; 770 771 } while (!std::is_sorted(foo.begin(), foo.end())); 772 773 std::cout << "the range is sorted!\n"; 774 } 775 776 { 777 std::array<int, 4> foo{ 2, 4, 1, 3 }; 778 std::array<int, 4>::iterator it; 779 780 do { 781 // try a new permutation: 782 std::prev_permutation(foo.begin(), foo.end()); 783 784 // print range: 785 std::cout << "foo:"; 786 for (int& x : foo) std::cout << ' ' << x; 787 it = std::is_sorted_until(foo.begin(), foo.end()); 788 std::cout << " (" << (it - foo.begin()) << " elements sorted)\n"; 789 790 } while (it != foo.end()); 791 792 std::cout << "the range is sorted!\n"; 793 } 794 795 { 796 std::vector<int> myvector; 797 798 // set some values: 799 for (int i = 1; i<10; i++) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 800 801 std::random_shuffle(myvector.begin(), myvector.end()); 802 803 // using default comparison (operator <): 804 std::nth_element(myvector.begin(), myvector.begin() + 5, myvector.end()); 805 806 // using function as comp 807 std::nth_element(myvector.begin(), myvector.begin() + 5, myvector.end(), myfunction2); 808 809 // print out content: 810 std::cout << "myvector contains:"; 811 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 812 std::cout << ' ' << *it; // 1 2 3 4 5 6 7 8 9 813 std::cout << '\n'; 814 } 815 816 { 817 int myints[] = { 9, 8, 7, 6, 5, 4, 3, 2, 1 }; 818 std::vector<int> myvector(myints, myints + 9); 819 820 // using default comparison (operator <): 821 std::partial_sort(myvector.begin(), myvector.begin() + 5, myvector.end()); 822 823 // using function as comp 824 std::partial_sort(myvector.begin(), myvector.begin() + 5, myvector.end(), myfunction2); 825 826 // print out content: 827 std::cout << "myvector contains:"; 828 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 829 std::cout << ' ' << *it; // 1 2 3 4 5 9 8 7 6 830 std::cout << '\n'; 831 } 832 833 { 834 int myints[] = { 9, 8, 7, 6, 5, 4, 3, 2, 1 }; 835 std::vector<int> myvector(5); 836 837 // using default comparison (operator <): 838 std::partial_sort_copy(myints, myints + 9, myvector.begin(), myvector.end()); 839 840 // using function as comp 841 std::partial_sort_copy(myints, myints + 9, myvector.begin(), myvector.end(), myfunction2); 842 843 // print out content: 844 std::cout << "myvector contains:"; 845 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 846 std::cout << ' ' << *it; // 1 2 3 4 5 847 std::cout << '\n'; 848 } 849 850 { 851 int myints[] = { 32, 71, 12, 45, 26, 80, 53, 33 }; 852 std::vector<int> myvector(myints, myints + 8); // 32 71 12 45 26 80 53 33 853 854 // using default comparison (operator <): 855 std::sort(myvector.begin(), myvector.begin() + 4); //(12 32 45 71)26 80 53 33 856 857 // using function as comp 858 std::sort(myvector.begin() + 4, myvector.end(), myfunction2); // 12 32 45 71(26 33 53 80) 859 860 // using object as comp 861 std::sort(myvector.begin(), myvector.end(), myobject2); //(12 26 32 33 45 53 71 80) 862 863 // print out content: 864 std::cout << "myvector contains:"; 865 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 866 std::cout << ' ' << *it; // 12 26 32 33 45 53 71 80 867 std::cout << '\n'; 868 } 869 870 { 871 double mydoubles[] = { 3.14, 1.41, 2.72, 4.67, 1.73, 1.32, 1.62, 2.58 }; 872 873 std::vector<double> myvector; 874 875 myvector.assign(mydoubles, mydoubles + 8); 876 877 std::cout << "using default comparison:"; 878 std::stable_sort(myvector.begin(), myvector.end()); 879 for (std::vector<double>::iterator it = myvector.begin(); it != myvector.end(); ++it) 880 std::cout << ' ' << *it; // 1.32 1.41 1.62 1.73 2.58 2.72 3.14 4.67 881 std::cout << '\n'; 882 883 myvector.assign(mydoubles, mydoubles + 8); 884 885 std::cout << "using 'compare_as_ints' :"; 886 std::stable_sort(myvector.begin(), myvector.end(), compare_as_ints); 887 for (std::vector<double>::iterator it = myvector.begin(); it != myvector.end(); ++it) 888 std::cout << ' ' << *it; // 1.41 1.73 1.32 1.62 2.72 2.58 3.14 4.67 889 std::cout << '\n'; 890 } 891 892 return 0; 893 } 894 895 //////////////////////////////////////////////////// 896 int test_algorithm_swap() 897 { 898 { 899 int myints[] = { 10, 20, 30, 40, 50 }; // myints: 10 20 30 40 50 900 std::vector<int> myvector(4, 99); // myvector: 99 99 99 99 901 902 std::iter_swap(myints, myvector.begin()); // myints: [99] 20 30 40 50 903 // myvector: [10] 99 99 99 904 905 std::iter_swap(myints + 3, myvector.begin() + 2); // myints: 99 20 30 [99] 50 906 // myvector: 10 99 [40] 99 907 908 std::cout << "myvector contains:"; 909 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 910 std::cout << ' ' << *it; // 10 99 40 99 911 std::cout << '\n'; 912 } 913 914 { 915 int x = 10, y = 20; // x:10 y:20 916 std::swap(x, y); // x:20 y:10 917 918 std::vector<int> foo(4, x), bar(6, y); // foo:4x20 bar:6x10 919 std::swap(foo, bar); // foo:6x10 bar:4x20 920 921 std::cout << "foo contains:"; 922 for (std::vector<int>::iterator it = foo.begin(); it != foo.end(); ++it) 923 std::cout << ' ' << *it; // 10 10 10 10 10 10 924 std::cout << '\n'; 925 } 926 927 { 928 std::vector<int> foo(5, 10); // foo: 10 10 10 10 10 929 std::vector<int> bar(5, 33); // bar: 33 33 33 33 33 930 931 std::swap_ranges(foo.begin() + 1, foo.end() - 1, bar.begin()); 932 933 // print out results of swap: 934 std::cout << "foo contains:"; 935 for (std::vector<int>::iterator it = foo.begin(); it != foo.end(); ++it) 936 std::cout << ' ' << *it; // 10 33 33 33 10 937 std::cout << '\n'; 938 939 std::cout << "bar contains:"; 940 for (std::vector<int>::iterator it = bar.begin(); it != bar.end(); ++it) 941 std::cout << ' ' << *it; // 10 10 10 33 33 942 std::cout << '\n'; 943 } 944 945 return 0; 946 } 947 948 /////////////////////////////////////////////// 949 static bool mycomp(char c1, char c2) { return std::tolower(c1)<std::tolower(c2); } 950 951 int test_algorithm_lexicographical_compare() 952 { 953 char foo[] = "Apple"; 954 char bar[] = "apartment"; 955 956 std::cout << std::boolalpha; 957 958 std::cout << "Comparing foo and bar lexicographically (foo<bar):\n"; 959 960 std::cout << "Using default comparison (operator<): "; 961 std::cout << std::lexicographical_compare(foo, foo + 5, bar, bar + 9); // true 962 std::cout << '\n'; 963 964 std::cout << "Using mycomp as comparison object: "; 965 std::cout << std::lexicographical_compare(foo, foo + 5, bar, bar + 9, mycomp); // false 966 std::cout << '\n'; 967 968 return 0; 969 } 970 971 ////////////////////////////////////// 972 static bool myfn(int i, int j) { return i<j; } 973 974 int test_algorithm_min_max() 975 { 976 { 977 std::cout << "min(1, 2)==" << std::min(1, 2) << '\n'; // 1 978 std::cout << "min(2, 1)==" << std::min(2, 1) << '\n'; // 1 979 std::cout << "min('a', 'z')==" << std::min('a', 'z') << '\n'; // a 980 std::cout << "min(3.14, 2.72)==" << std::min(3.14, 2.72) << '\n'; // 2.72 981 } 982 983 { 984 int myints[] = { 3, 7, 2, 5, 6, 4, 9 }; 985 986 // using default comparison: 987 std::cout << "The smallest element is " << *std::min_element(myints, myints + 7) << '\n'; // 2 988 std::cout << "The largest element is " << *std::max_element(myints, myints + 7) << '\n'; // 9 989 990 // using function myfn as comp: 991 std::cout << "The smallest element is " << *std::min_element(myints, myints + 7, myfn) << '\n'; // 2 992 std::cout << "The largest element is " << *std::max_element(myints, myints + 7, myfn) << '\n'; // 9 993 994 // using object myobj as comp: 995 std::cout << "The smallest element is " << *std::min_element(myints, myints + 7, myobject2) << '\n'; // 2 996 std::cout << "The largest element is " << *std::max_element(myints, myints + 7, myobject2) << '\n'; // 9 997 } 998 999 { 1000 std::cout << "max(1,2)==" << std::max(1, 2) << '\n'; // 2 1001 std::cout << "max(2,1)==" << std::max(2, 1) << '\n'; // 2 1002 std::cout << "max('a','z')==" << std::max('a', 'z') << '\n'; // z 1003 std::cout << "max(3.14,2.73)==" << std::max(3.14, 2.73) << '\n'; // 3.14 1004 } 1005 1006 { 1007 auto result = std::minmax({ 1, 2, 3, 4, 5 }); 1008 1009 std::cout << "minmax({1,2,3,4,5}): "; 1010 std::cout << result.first << ' ' << result.second << '\n'; // 1 5 1011 } 1012 1013 { 1014 std::array<int, 7> foo{ 3, 7, 2, 9, 5, 8, 6 }; 1015 1016 auto result = std::minmax_element(foo.begin(), foo.end()); 1017 1018 // print result: 1019 std::cout << "min is " << *result.first; // 2 1020 std::cout << ", at position " << (result.first - foo.begin()) << '\n'; // 2 1021 std::cout << "max is " << *result.second; // 9 1022 std::cout << ", at position " << (result.second - foo.begin()) << '\n'; // 3 1023 } 1024 1025 return 0; 1026 } 1027 1028 /////////////////////////////////////////// 1029 int test_algorithm_mismatch() 1030 { 1031 std::vector<int> myvector; 1032 for (int i = 1; i<6; i++) myvector.push_back(i * 10); // myvector: 10 20 30 40 50 1033 1034 int myints[] = { 10, 20, 80, 320, 1024 }; // myints: 10 20 80 320 1024 1035 1036 std::pair<std::vector<int>::iterator, int*> mypair; 1037 1038 // using default comparison: 1039 mypair = std::mismatch(myvector.begin(), myvector.end(), myints); 1040 std::cout << "First mismatching elements: " << *mypair.first; // 30 1041 std::cout << " and " << *mypair.second << '\n'; // 80 1042 1043 ++mypair.first; ++mypair.second; 1044 1045 // using predicate comparison: 1046 mypair = std::mismatch(mypair.first, myvector.end(), mypair.second, mypredicate); 1047 std::cout << "Second mismatching elements: " << *mypair.first; // 40 1048 std::cout << " and " << *mypair.second << '\n'; // 320 1049 1050 return 0; 1051 } 1052 1053 ////////////////////////////////////////// 1054 /* The behavior of std::move_backward template is equivalent to: 1055 template<class BidirectionalIterator1, class BidirectionalIterator2> 1056 BidirectionalIterator2 move_backward ( BidirectionalIterator1 first, 1057 BidirectionalIterator1 last, 1058 BidirectionalIterator2 result ) 1059 { 1060 while (last!=first) *(--result) = std::move(*(--last)); 1061 return result; 1062 } 1063 */ 1064 int test_algorithm_move() 1065 { 1066 { 1067 std::vector<std::string> foo = { "air", "water", "fire", "earth" }; 1068 std::vector<std::string> bar(4); 1069 1070 // moving ranges: 1071 std::cout << "Moving ranges...\n"; 1072 std::move(foo.begin(), foo.begin() + 4, bar.begin()); 1073 1074 std::cout << "foo contains " << foo.size() << " elements:";// 4 1075 std::cout << " (each in an unspecified but valid state)"; 1076 std::cout << '\n'; 1077 1078 std::cout << "bar contains " << bar.size() << " elements:"; // 4 1079 for (std::string& x : bar) std::cout << " [" << x << "]"; // [air] [water] [fire] [earch] 1080 std::cout << '\n'; 1081 1082 // moving container: 1083 std::cout << "Moving container...\n"; 1084 foo = std::move(bar); 1085 1086 std::cout << "foo contains " << foo.size() << " elements:"; // 4 1087 for (std::string& x : foo) std::cout << " [" << x << "]"; // [air] [water] [fire] [earch] 1088 std::cout << '\n'; 1089 std::cout << "bar contains " << bar.size() << " elements" << std::endl; // 0 1090 //std::cout << "bar is in an unspecified but valid state"; 1091 //std::cout << '\n'; 1092 } 1093 1094 { 1095 std::string elems[10] = { "air", "water", "fire", "earth" }; 1096 1097 // insert new element at the beginning: 1098 std::move_backward(elems, elems + 4, elems + 5); 1099 elems[0] = "ether"; 1100 1101 std::cout << "elems contains:"; 1102 for (int i = 0; i<10; ++i) 1103 std::cout << " [" << elems[i] << "]"; // [ether] [air] [water] [fire] [earch] 1104 std::cout << '\n'; 1105 } 1106 1107 return 0; 1108 } 1109 1110 ////////////////////////////////////////////// 1111 // random generator function: 1112 int myrandom(int i) { return std::rand() % i; } 1113 1114 int test_algorithm_shuffle() 1115 { 1116 { 1117 std::srand(unsigned(std::time(0))); 1118 std::vector<int> myvector; 1119 1120 // set some values: 1121 for (int i = 1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 1122 1123 // using built-in random generator: 1124 std::random_shuffle(myvector.begin(), myvector.end()); 1125 1126 // using myrandom: 1127 std::random_shuffle(myvector.begin(), myvector.end(), myrandom); 1128 1129 // print out content: 1130 std::cout << "myvector contains:"; 1131 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1132 std::cout << ' ' << *it; 1133 1134 std::cout << '\n'; 1135 } 1136 1137 { 1138 std::array<int, 5> foo{ 1, 2, 3, 4, 5 }; 1139 1140 // obtain a time-based seed: 1141 unsigned seed = std::chrono::system_clock::now().time_since_epoch().count(); 1142 1143 shuffle(foo.begin(), foo.end(), std::default_random_engine(seed)); 1144 1145 std::cout << "shuffled elements:"; 1146 for (int& x : foo) std::cout << ' ' << x; 1147 std::cout << '\n'; 1148 } 1149 1150 return 0; 1151 } 1152 1153 ////////////////////////////////////////// 1154 int test_algorithm_remove() 1155 { 1156 { 1157 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; // 10 20 30 30 20 10 10 20 1158 1159 // bounds of range: 1160 int* pbegin = myints; // ^ 1161 int* pend = myints + sizeof(myints) / sizeof(int); // ^ ^ 1162 1163 pend = std::remove(pbegin, pend, 20); // 10 30 30 10 10 ? ? ? 1164 // ^ ^ 1165 std::cout << "range contains:"; 1166 for (int* p = pbegin; p != pend; ++p) 1167 std::cout << ' ' << *p; // 10 30 30 10 10 1168 std::cout << '\n'; 1169 } 1170 1171 { 1172 int myints[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; // 1 2 3 4 5 6 7 8 9 1173 1174 // bounds of range: 1175 int* pbegin = myints; // ^ 1176 int* pend = myints + sizeof(myints) / sizeof(int); // ^ ^ 1177 1178 pend = std::remove_if(pbegin, pend, IsOdd); // 2 4 6 8 ? ? ? ? ? 1179 // ^ ^ 1180 std::cout << "the range contains:"; 1181 for (int* p = pbegin; p != pend; ++p) 1182 std::cout << ' ' << *p; // 2 4 6 8 1183 std::cout << '\n'; 1184 } 1185 1186 { 1187 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; // 10 20 30 30 20 10 10 20 1188 std::vector<int> myvector(8); 1189 1190 std::remove_copy(myints, myints + 8, myvector.begin(), 20); // 10 30 30 10 10 0 0 0 1191 1192 std::cout << "myvector contains:"; 1193 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1194 std::cout << ' ' << *it; // 10 30 30 10 10 0 0 0 1195 std::cout << '\n'; 1196 } 1197 1198 { 1199 int myints[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 1200 std::vector<int> myvector(9); 1201 1202 std::remove_copy_if(myints, myints + 9, myvector.begin(), IsOdd); 1203 1204 std::cout << "myvector contains:"; 1205 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1206 std::cout << ' ' << *it; // 2 4 6 8 0 0 0 0 0 1207 std::cout << '\n'; 1208 } 1209 1210 return 0; 1211 } 1212 1213 ////////////////////////////////////////////// 1214 int test_algorithm_replace() 1215 { 1216 { 1217 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; 1218 std::vector<int> myvector(myints, myints + 8); // 10 20 30 30 20 10 10 20 1219 1220 std::replace(myvector.begin(), myvector.end(), 20, 99); // 10 99 30 30 99 10 10 99 1221 1222 std::cout << "myvector contains:"; 1223 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1224 std::cout << ' ' << *it; // 10 99 30 30 99 10 10 99 1225 std::cout << '\n'; 1226 } 1227 1228 { 1229 std::vector<int> myvector; 1230 1231 // set some values: 1232 for (int i = 1; i<10; i++) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 1233 1234 std::replace_if(myvector.begin(), myvector.end(), IsOdd, 0); // 0 2 0 4 0 6 0 8 0 1235 1236 std::cout << "myvector contains:"; 1237 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1238 std::cout << ' ' << *it; // 0 2 0 4 0 6 0 8 0 1239 std::cout << '\n'; 1240 } 1241 1242 { 1243 int myints[] = { 10, 20, 30, 30, 20, 10, 10, 20 }; 1244 1245 std::vector<int> myvector(8); 1246 std::replace_copy(myints, myints + 8, myvector.begin(), 20, 99); 1247 1248 std::cout << "myvector contains:"; 1249 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1250 std::cout << ' ' << *it; // 10 99 30 30 99 10 10 99 1251 std::cout << '\n'; 1252 } 1253 1254 { 1255 std::vector<int> foo, bar; 1256 1257 // set some values: 1258 for (int i = 1; i<10; i++) foo.push_back(i); // 1 2 3 4 5 6 7 8 9 1259 1260 bar.resize(foo.size()); // allocate space 1261 std::replace_copy_if(foo.begin(), foo.end(), bar.begin(), IsOdd, 0); // 0 2 0 4 0 6 0 8 0 1262 1263 std::cout << "bar contains:"; 1264 for (std::vector<int>::iterator it = bar.begin(); it != bar.end(); ++it) 1265 std::cout << ' ' << *it; // 0 2 0 4 0 6 0 8 0 1266 std::cout << '\n'; 1267 } 1268 1269 return 0; 1270 } 1271 1272 /////////////////////////////////////////////////// 1273 int test_algorithm_reverse() 1274 { 1275 { 1276 std::vector<int> myvector; 1277 1278 // set some values: 1279 for (int i = 1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 1280 1281 std::reverse(myvector.begin(), myvector.end()); // 9 8 7 6 5 4 3 2 1 1282 1283 // print out content: 1284 std::cout << "myvector contains:"; 1285 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1286 std::cout << ' ' << *it; // 9 8 7 6 5 4 3 2 1 1287 std::cout << '\n'; 1288 } 1289 1290 { 1291 int myints[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 1292 std::vector<int> myvector; 1293 1294 myvector.resize(9); // allocate space 1295 1296 std::reverse_copy(myints, myints + 9, myvector.begin()); 1297 1298 // print out content: 1299 std::cout << "myvector contains:"; 1300 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1301 std::cout << ' ' << *it; // 9 8 7 6 5 4 3 2 1 1302 1303 std::cout << '\n'; 1304 } 1305 1306 return 0; 1307 } 1308 1309 //////////////////////////////////////////// 1310 /* 1311 The behavior of std::rotate template (C++98) is equivalent to: 1312 template <class ForwardIterator> 1313 void rotate (ForwardIterator first, ForwardIterator middle, ForwardIterator last) 1314 { 1315 ForwardIterator next = middle; 1316 while (first!=next) { 1317 swap (*first++,*next++); 1318 if (next==last) next=middle; 1319 else if (first==middle) middle=next; 1320 } 1321 } 1322 */ 1323 1324 int test_algorithm_rotate() 1325 { 1326 { 1327 std::vector<int> myvector; 1328 1329 // set some values: 1330 for (int i = 1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9 1331 1332 std::rotate(myvector.begin(), myvector.begin() + 3, myvector.end()); // 4 5 6 7 8 9 1 2 3 1333 // print out content: 1334 std::cout << "myvector contains:"; 1335 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1336 std::cout << ' ' << *it; // 4 5 6 7 8 9 1 2 3 1337 std::cout << '\n'; 1338 } 1339 1340 { 1341 int myints[] = { 10, 20, 30, 40, 50, 60, 70 }; 1342 1343 std::vector<int> myvector(7); 1344 1345 std::rotate_copy(myints, myints + 3, myints + 7, myvector.begin()); 1346 1347 // print out content: 1348 std::cout << "myvector contains:"; 1349 for (std::vector<int>::iterator it = myvector.begin(); it != myvector.end(); ++it) 1350 std::cout << ' ' << *it; // 40 50 60 70 10 20 30 1351 std::cout << '\n'; 1352 } 1353 1354 return 0; 1355 } 1356 1357 ////////////////////////////////////// 1358 /* 1359 The behavior of std::set_difference template is equivalent to: 1360 template <class InputIterator1, class InputIterator2, class OutputIterator> 1361 OutputIterator set_difference (InputIterator1 first1, InputIterator1 last1, 1362 InputIterator2 first2, InputIterator2 last2, OutputIterator result) 1363 { 1364 while (first1!=last1 && first2!=last2) { 1365 if (*first1<*first2) { *result = *first1; ++result; ++first1; } 1366 else if (*first2<*first1) ++first2; 1367 else { ++first1; ++first2; } 1368 } 1369 return std::copy(first1,last1,result); 1370 } 1371 */ 1372 1373 int test_algorithm_set() 1374 { 1375 { 1376 int first[] = { 5, 10, 15, 20, 25 }; 1377 int second[] = { 50, 40, 30, 20, 10 }; 1378 std::vector<int> v(10); // 0 0 0 0 0 0 0 0 0 0 1379 std::vector<int>::iterator it; 1380 1381 std::sort(first, first + 5); // 5 10 15 20 25 1382 std::sort(second, second + 5); // 10 20 30 40 50 1383 1384 it = std::set_difference(first, first + 5, second, second + 5, v.begin()); 1385 // 5 15 25 0 0 0 0 0 0 0 1386 v.resize(it - v.begin()); // 5 15 25 1387 1388 std::cout << "The difference has " << (v.size()) << " elements:\n"; // 3 1389 for (it = v.begin(); it != v.end(); ++it) 1390 std::cout << ' ' << *it; // 5 15 25 1391 std::cout << '\n'; 1392 } 1393 1394 { 1395 int first[] = { 5, 10, 15, 20, 25 }; 1396 int second[] = { 50, 40, 30, 20, 10 }; 1397 std::vector<int> v(10); // 0 0 0 0 0 0 0 0 0 0 1398 std::vector<int>::iterator it; 1399 1400 std::sort(first, first + 5); // 5 10 15 20 25 1401 std::sort(second, second + 5); // 10 20 30 40 50 1402 1403 it = std::set_intersection(first, first + 5, second, second + 5, v.begin()); 1404 // 10 20 0 0 0 0 0 0 0 0 1405 v.resize(it - v.begin()); // 10 20 1406 1407 std::cout << "The intersection has " << (v.size()) << " elements:\n"; // 2 1408 for (it = v.begin(); it != v.end(); ++it) 1409 std::cout << ' ' << *it; // 10 20 1410 std::cout << '\n'; 1411 } 1412 1413 { 1414 int first[] = { 5, 10, 15, 20, 25 }; 1415 int second[] = { 50, 40, 30, 20, 10 }; 1416 std::vector<int> v(10); // 0 0 0 0 0 0 0 0 0 0 1417 std::vector<int>::iterator it; 1418 1419 std::sort(first, first + 5); // 5 10 15 20 25 1420 std::sort(second, second + 5); // 10 20 30 40 50 1421 1422 it = std::set_symmetric_difference(first, first + 5, second, second + 5, v.begin()); 1423 // 5 15 25 30 40 50 0 0 0 0 1424 v.resize(it - v.begin()); // 5 15 25 30 40 50 1425 1426 std::cout << "The symmetric difference has " << (v.size()) << " elements:\n"; // 6 1427 for (it = v.begin(); it != v.end(); ++it) 1428 std::cout << ' ' << *it; // 5 15 25 30 40 50 1429 std::cout << '\n'; 1430 } 1431 1432 { 1433 int first[] = { 5, 10, 15, 20, 25 }; 1434 int second[] = { 50, 40, 30, 20, 10 }; 1435 std::vector<int> v(10); // 0 0 0 0 0 0 0 0 0 0 1436 std::vector<int>::iterator it; 1437 1438 std::sort(first, first + 5); // 5 10 15 20 25 1439 std::sort(second, second + 5); // 10 20 30 40 50 1440 1441 it = std::set_union(first, first + 5, second, second + 5, v.begin()); 1442 // 5 10 15 20 25 30 40 50 0 0 1443 v.resize(it - v.begin()); // 5 10 15 20 25 30 40 50 1444 1445 std::cout << "The union has " << (v.size()) << " elements:\n"; // 8 1446 for (it = v.begin(); it != v.end(); ++it) 1447 std::cout << ' ' << *it; // 5 10 15 20 25 30 40 50 1448 std::cout << '\n'; 1449 } 1450 1451 return 0; 1452 } 1453 1454 ///////////////////////////////////// 1455 int op_increase(int i) { return ++i; } 1456 1457 int test_algorithm_transform() 1458 { 1459 std::vector<int> foo; 1460 std::vector<int> bar; 1461 1462 // set some values: 1463 for (int i = 1; i<6; i++) 1464 foo.push_back(i * 10); // foo: 10 20 30 40 50 1465 1466 bar.resize(foo.size()); // allocate space 1467 1468 std::transform(foo.begin(), foo.end(), bar.begin(), op_increase); 1469 // bar: 11 21 31 41 51 1470 1471 // std::plus adds together its two arguments: 1472 std::transform(foo.begin(), foo.end(), bar.begin(), foo.begin(), std::plus<int>()); 1473 // foo: 21 41 61 81 101 1474 1475 std::cout << "foo contains:"; 1476 for (std::vector<int>::iterator it = foo.begin(); it != foo.end(); ++it) 1477 std::cout << ' ' << *it; // 21 41 61 81 101 1478 std::cout << '\n'; 1479 1480 return 0; 1481 } 1482 1483 ///////////////////////////////////////// 1484 int test_algorithm_unique() 1485 { 1486 { 1487 int myints[] = { 10, 20, 20, 20, 30, 30, 20, 20, 10 }; // 10 20 20 20 30 30 20 20 10 1488 std::vector<int> myvector(myints, myints + 9); 1489 1490 // using default comparison: 1491 std::vector<int>::iterator it; 1492 it = std::unique(myvector.begin(), myvector.end()); // 10 20 30 20 10 ? ? ? ? 1493 // ^ 1494 1495 myvector.resize(std::distance(myvector.begin(), it)); // 10 20 30 20 10 1496 1497 // using predicate comparison: 1498 std::unique(myvector.begin(), myvector.end(), myfunction); // (no changes) 1499 1500 // print out content: 1501 std::cout << "myvector contains:"; 1502 for (it = myvector.begin(); it != myvector.end(); ++it) 1503 std::cout << ' ' << *it; // 10 20 30 20 10 1504 std::cout << '\n'; 1505 } 1506 1507 { 1508 int myints[] = { 10, 20, 20, 20, 30, 30, 20, 20, 10 }; 1509 std::vector<int> myvector(9); // 0 0 0 0 0 0 0 0 0 1510 1511 // using default comparison: 1512 std::vector<int>::iterator it; 1513 it = std::unique_copy(myints, myints + 9, myvector.begin()); // 10 20 30 20 10 0 0 0 0 1514 // ^ 1515 1516 std::sort(myvector.begin(), it); // 10 10 20 20 30 0 0 0 0 1517 // ^ 1518 1519 // using predicate comparison: 1520 it = std::unique_copy(myvector.begin(), it, myvector.begin(), myfunction); 1521 // 10 20 30 20 30 0 0 0 0 1522 // ^ 1523 1524 myvector.resize(std::distance(myvector.begin(), it)); // 10 20 30 1525 1526 // print out content: 1527 std::cout << "myvector contains:"; 1528 for (it = myvector.begin(); it != myvector.end(); ++it) 1529 std::cout << ' ' << *it; // 10 20 30 1530 std::cout << '\n'; 1531 } 1532 1533 return 0; 1534 } 1535 1536 } // namespace algorithm_
