c++ 标准类库中几个简单的通用算法

#include <iostream> #include <vector> #include <string> #include <algorithm>//通用算法头文件 using namespace std; void foreach(string str) { cout<<str<<endl; } bool isWorld(string& str) { if(str == "world") { return true; } return false; } void main() { cout<<"OK,JUST DO IT!!"<<endl; vector<string> strA; strA.push_back("I am the first string!"); strA.push_back("I am the second string!"); strA.push_back("I am the third string !"); strA.push_back("hello"); strA.push_back("world"); strA.push_back("hello"); strA.push_back("hello"); strA.push_back("world"); cout<<"for research strA---------------------------------"<<endl; for( vector<string>::iterator it = strA.begin(); it != strA.end(); it++ ) { cout<<*it<<endl; } cout<<"for_each research strA----------------------------"<<endl; for_each(strA.begin(),strA.end(),foreach); string dis = "hello"; int num = count( strA.begin(), strA.end(), dis ); cout<<"there are "<<num<<" of \"hello\" string!"<<endl; //第三个参数可以是一个函数，还可以是一个类（含有operator），要求返回值要求均为bool型 num = count_if( strA.begin(), strA.end(), isWorld ); cout<<"there are "<<num<<" of \"world\" string!"<<endl; string strWorld = "world"; //find前两个参数是iterator(迭代器)，表示查找半闭合区间的前后两个位置 //第三个参数是于strA容器中相匹配的数据类型的一个对象 vector<string>::iterator itWorld = find( strA.begin(), strA.end(), strWorld); if( itWorld != strA.end() ) { cout<<"find "<<*itWorld<<endl; } else { cout<<"not find!"<<endl; } itWorld = find_if( strA.begin(), strA.end(), isWorld ); if( itWorld != strA.end() ) { cout<<"find_if "<<*itWorld<<endl; } else { cout<<"not find_if!"<<endl; } vector<string> strSearch; strSearch.push_back("hello"); strSearch.push_back("world"); //search()算法，它是搜索的一个范围，如果成功返回一个指着strA中第一个于strSearch匹配的iterator，否侧返回strA的end() //find和find_if算法查找的是容器的第一个匹配的值 vector<string>::iterator itSearch = search( strA.begin(), strA.end(), strSearch.begin(), strSearch.end() ); if( itSearch != strA.end() ) { cout<<"search success!"<<endl; } else { cout<<"search fail!"<<endl; } //sort()算法只使用于可以随机访问的类型，vector可以，list不可以，他有自己的sort算法 sort(strA.begin(),strA.end()); cout<<"after sort ----------------------------------------"<<endl; for_each(strA.begin(),strA.end(),foreach); }