c++ stl algorithm: std::find, std::find_if

 

from 

http://blog.csdn.net/ilysony/article/details/6526545

std::find:
    查找容器元素, find只能查找容器元素为<基本数据类型>
   
[cpp] view plaincopy
#include <iostream>  
#include <vector>  
#include <algorithm>  
int main()  
{  
    std::vector<int> v;  
    for (int i = 0; i < 10; ++i)  
        v.push_back(i);  
    std::vector<int>::iterator iter = std::find(v.begin(), v.end(), 3);  
    if (iter == v.end())  
        std::cout << "can not find value 3 in v" << std::endl;  
    else  
        std::cout << "the index of value " << (*iter) << " is " << std::distance(v.begin(), iter) << std::endl;  
    return 0;  
}  

 
 
std::find_if
    按条件查找容器元素, 容器类型为<类>时, 无法使用find来查找,  所以要使用find_if来查找
   
[cpp] view plaincopy
#include <iostream>  
#include <vector>  
#include <algorithm>  
#include <functional>  
struct Point  
{  
    int x;  
    int y;  
};  
struct PointFindByCoord : public std::binary_function<Point, Point, bool>  
{  
    bool operator () (const Point &obj1, const Point &obj2) const  
    {  
        return obj1.x == obj2.x && obj1.y == obj2.y;  
    }  
};  
int main()  
{  
    std::vector<Point> v;  
    for (int i = 0; i < 5; ++i)  
    {  
        for (int j = 0; j < 5; ++j)  
        {  
            Point pt;  
            pt.x = i;  
            pt.y = j;  
            v.push_back(pt);  
        }  
    }  
    Point needFind;  
    needFind.x = 4;  
    needFind.y = 3;  
    std::vector<Point>::iterator iter = std::find_if(v.begin(), v.end(), std::bind2nd(PointFindByCoord(), needFind));  
    if (iter == v.end())  
    {  
        // 未找到  
    }  
    else  
        std::cout << "the index of value Point(" << (*iter).x << ", " << (*iter).y  
            << ") is " << std::distance(v.begin(), iter) << std::endl;  
      
    return 0;  
}  

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