vector的用法总结
Reference
Constructors
vector
Constructs a vector of a specific size or with elements of a specific value or with a specific allocator or as a copy of some other vector.
Typedefs
allocator_type
A type that represents the allocator class for the vector object.
const_iterator
A type that provides a random-access iterator that can read a const element in a vector.
const_pointer
A type that provides a pointer to a const element in a vector.
const_reference
A type that provides a reference to a const element stored in a vector for reading and performing const operations.
const_reverse_iterator
A type that provides a random-access iterator that can read any const element in the vector.
difference_type
A type that provides the difference between the addresses of two elements in a vector.
两个元素在vector中的地址差，不是真实的元素地址差
iterator
A type that provides a random-access iterator that can read or modify any element in a vector.
pointer
A type that provides a pointer to an element in a vector.
reference
A type that provides a reference to an element stored in a vector.
reverse_iterator
A type that provides a random-access iterator that can read or modify any element in a reversed vector.
size_type
A type that counts the number of elements in a vector.
value_type
A type that represents the data type stored in a vector.
Member Functions
assign
Erases a vector and copies the specified elements to the empty vector.
清除原有的vector容器，然指定特定的元素到vector
例如：
vector<int>vec；
vec.assign(10,250);擦除原有容器的内容，插入10个值为250的元素
vec1(vec.rbegin,vec,rend);将vec1某个迭代范围内的元素插入到vec1
at
Returns a reference to the element at a specified location in the vector.
例如：
vec.at(3);返回第三个数的引用
back
Returns a reference to the last element of the vector.
如果vector为空，使用导致coredump)
begin
Returns a random-access iterator to the first element in the container.
如果vector为空，begin返回的迭代器与end返回的迭代器相同。
capacity
Returns the number of elements that the vector could contain without allocating more storage.
获取在不重新分配内存的情况下可容纳的元素最大数量
clear
Erases the elements of the vector.
清空整个容器
vec.clear();
empty
Tests if the vector container is empty.
end
Returns a random-access iterator that points just beyond the end of the vector.
返回的迭代器指向vector的“末端元素的下一个”。
通常称为超出末端迭代器(off-the-end iterator)，表明它指向了一个不存在的元素。
erase
Removes an element or a range of elements in a vector from specified positions.
可通过迭代器清除某个元素或者某一迭代范围内的元素，返回原元素后一个元素在删除后的vector中的迭代器或者end()。
例如：
vector<int>::iterator iter = ++vec.begin();
vec.erase(iter);
vec.erase(vec.begin(),--vec.end());
front
Returns a reference to the first element in a vector.
如果vector为空，使用导致coredump
get_allocator
Returns an object to the allocator class used by a vector.
insert
Inserts an element or a number of elements into the vector at a specified position.
max_size
Returns the maximum length of the vector.
vector可容纳元素的最大数量，vs08在win64测试最大貌似是1073741823
pop_back
Deletes the element at the end of the vector.
push_back
Add an element to the end of the vector.
调用元素类型的拷贝构造函数以其值为模板初始化新变量，放入到vector的末尾。
rbegin
Returns an iterator to the first element in a reversed vector.
返回反向迭代器，指向vector的最后一个元素
rend
Returns an iterator to the end of a reversed vector.
reserve
Reserves a minimum length of storage for a vector object.
改变当前vector的预留容量，在vs08上测试，如果预留容量小于当前元素个数不会改变，在大于的时候才会改变。
resize
Specifies a new size for a vector.
在vs08上测试，如果当前的元素size大于这个resize值,会从头到尾截断resize大小，后面的元素舍弃，当前size元素小于的话
多出来的新元素都需以元素类型的default构造函数构造完成。
void resize(size_type n, value_type x);
将元素数量改为n，如果vector因此变大了，多出来的元素都是x的副本
size
Returns the number of elements in the vector.
swap
Exchanges the elements of two vectors.
交换两个vec
campare function（非成员函数） 这个时候就要注意元素的比较重载函数了
inline bool operator == (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断两个vector是否相等。首先比较二者的元素个数是否相同；如果个数相同则遍历vector，调用元素的“==”运算符比较是否相同。
inline bool operator == (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断两个vector是否相等。首先比较二者的元素个数是否相同；如果个数相同则遍历vector，调用元素的“==”运算符比较是否相同。
inline bool operator != (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断两个vector是否不等。结果为对“==”运算符的取反。
inline bool operator < (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断前者是否小于后者。遍历vector，返回第一对不满足“==”运算符的元素的“<”比较结果。
inline bool operator > (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断前者是否大于后者。遍历vector，返回第一对不满足“==”运算符的元素的“>”比较结果。
inline bool operator <= (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断前者是否"<="后者。结果为"!(rs < ls)"。
inline bool operator >= (const vector<T> & ls, const vector<T> & rs)
非成员函数，判断前者是否">="后者。结果为"!(ls < rs)"。
Operators
operator[]
Returns a reference to the vector element at a specified position.
