STL中的二元函数对象和二元谓词

古城微笑少年丶 2023-05-21 11:56 11阅读 0赞

二元函数对象：重载运算符()的函数有两个参数

二元谓词：函数有两个输入参数，并且返回值为bool类型

具体的可以看如下代码：

#include<iostream>
    using namespace std;
    #include "string"
    #include <vector>
    #include <list>
    #include "set"
    #include <algorithm>
    #include "functional"
    
    //二元函数对象
    template<typename T>
    class SumAdd
    {
    public:
    	T operator()(T& t1, T& t2)
    	{
    		return t1 + t2;
    	}
    };
    
    
    void main04()
    {
    	vector<int> v1, v2;
    	vector<int> v3;
    	v1.push_back(1);
    	v1.push_back(3);
    	v1.push_back(5);
    
    	v2.push_back(2);
    	v2.push_back(4);
    	v2.push_back(6);
    
    	v3.resize(10);
    
    	transform(v1.begin(),v1.end(),v2.begin(),v3.begin(), SumAdd<int>());
    
    	for (vector<int>::iterator it = v3.begin(); it != v3.end(); it++)
    	{
    		cout << *it << " ";   //输出3  7  11  0  0  0  0  0  0  0
    	}
    	cout << endl;
    }
    
    
    //二元谓词
    template<typename T>
    bool MyCompare(const T& a, const T& b)
    {
    	return a < b;
    }
    
    //普通函数
    void FuncShowElemt2(int& t)
    {
    	cout << t << " ";
    }
    
    void main()
    {
    	vector<int> v1(10);
    	for (int i = 0; i < 10; i++)
    	{
    		int tmp = rand() % 100;
    		v1[i] = tmp;
    	}
    
    	for (vector<int>::iterator it = v1.begin(); it != v1.end(); it++)
    	{
    		cout << *it << " ";  //输出：41 67 34 0 69 24 78 58 62 64 
    	}
    	cout << endl;
    	for_each(v1.begin(),v1.end(), FuncShowElemt2);
    	cout<<"排序之后.."<< endl;
    
    	sort(v1.begin(),v1.end(),MyCompare<int>);
    	for_each(v1.begin(),v1.end(), FuncShowElemt2);  //输出：0 24 34 41 58 62 64 67 69 78
    	cout << endl;
    }