变量（指针、数组）被创建之后应当及时把它们初始化
变量（指针、数组）被创建之后应当及时把它们初始化，以防止把 未被初始化的变量当成右值使用。
1 #include <iostream> 2 #include <string> 3 #include <map> 4 5 using namespace std; 6 7 //创建map的实例，整数(int)映射字符串(string) 8 typedef map<int, string> INT2STRING; 9 10 //测试map容器 11 /* run this program using the console pauser or add your own getch, system("pause") or input loop */ 12 13 int main(int argc, char** argv) { 14 //创建map对象theMap 15 INT2STRING theMap; 16 INT2STRING::iterator theIterator,it; 17 18 //向theMap容器中添入数据，数字和字符串配对 19 //每个元素是一个映射对 20 theMap.insert(INT2STRING::value_type(0,"Zero")); 21 theMap.insert(INT2STRING::value_type(2,"Two")); 22 theMap.insert(INT2STRING::value_type(4,"Four")); 23 theMap.insert(INT2STRING::value_type(6,"Six")); 24 theMap.insert(INT2STRING::value_type(8,"Eight")); 25 26 //显示map容器的所有对象 27 cout<<"theMap.begin()--theMap.end():"<<endl; 28 for (theIterator=theMap.begin();theIterator!=theMap.end();++theIterator){ 29 cout<<(*theIterator).first; 30 cout<<","<<(*theIterator).second<<" "; 31 } 32 cout<<endl; 33 34 //测试map容器key的惟一性 35 theMap.insert(INT2STRING::value_type(0,"Zero")); 36 theMap.insert(INT2STRING::value_type(1,"One")); 37 theMap.insert(INT2STRING::value_type(2,"Two")); 38 theMap.insert(INT2STRING::value_type(3,"Three")); 39 theMap.insert(INT2STRING::value_type(4,"Four")); 40 theMap.insert(INT2STRING::value_type(5,"Five")); 41 theMap.insert(INT2STRING::value_type(6,"Six")); 42 theMap.insert(INT2STRING::value_type(7,"Seven")); 43 theMap.insert(INT2STRING::value_type(8,"Eight")); 44 theMap.insert(INT2STRING::value_type(9,"Nine")); 45 //下列语句将不能插入到map容器中 46 theMap.insert(INT2STRING::value_type(5,"AAA")); 47 48 //显示map容器的所有对象 49 cout<<"theMap.begin()--theMap.end():"<<endl; 50 for (theIterator=theMap.begin();theIterator!=theMap.end();++theIterator){ 51 cout<<(*theIterator).first; 52 cout<<","<<(*theIterator).second<<" "; 53 } 54 cout<<endl; 55 56 //按键给定的区间显示序列中的元素 57 cout<<"[theMap.lower_bound(3),theMap.upper_bound(8)] :"<<endl; 58 for (it=theMap.lower_bound(3);it!=theMap.upper_bound(8);it++) { 59 cout<<(*it).first; 60 cout<<","<<(*it).second<<" "; 61 } 62 cout<<endl; 63 64 //显示theMap的状态信息 65 cout<<"theMap.size():"<<theMap.size()<<endl; 66 cout<<"theMap.max_size():"<<theMap.max_size()<<endl; 67 cout<<"theMap.count(15):"<<theMap.count(15)<<endl; 68 69 // 从键盘上输入数字，显示对应的字符串 70 string theString = ""; 71 int index; 72 for( ; ; ) 73 { 74 cout << "Enter \"q\" to quit, or enter a Number: "; 75 cin >> theString; 76 if(theString == "q") 77 break; 78 79 for(index = 0; index < theString.length(); index++){ 80 theIterator = theMap.find(theString[index] - '0'); 81 if(theIterator != theMap.end() ) 82 cout << (*theIterator).second << " "; 83 else 84 cout << "[err] "; 85 } 86 cout << endl; 87 } 88 return 0; 89 }
