目录

1.函数对象使用

 2.谓词

1.一元谓词

2.二元谓词

3.内建函数对象

1.算术仿函数

2.关系仿函数 

3.逻辑仿函数

---

1.函数对象使用

#include<bits/stdc++.h>
using namespace std;

class add
{
public:
	int operator()(int v1,int v2)
	{
		return v1 + v2;
	}
};

class print
{
public:
	void operator()(string s)
	{
		cout << s << endl;
	}
};

int main()
{
	add a;
	cout << a(5,6) << endl;
	
	print p;
	p("hello!!!!!");
	
	return 0;
}

 

 2.谓词

1.一元谓词

#include<bits/stdc++.h>
using namespace std;

class dayu5
{
public:
	bool operator()(int v)
	{
		return v > 5;
	}
};

int main()
{
	vector<int> v;
	v.push_back(7);
	v.push_back(9);
	v.push_back(5);
	v.push_back(100);
	v.push_back(3);
	
	//查找容器内有没有大于5的数
	//dayu5是匿名函数对象
	vector<int>::iterator it = find_if(v.begin(),v.end(),dayu5());
	//找到了返回迭代器位置，没找到时返回的是尾迭代器
	
	if(it != v.end()) cout << "找到了，开心。" << *it << endl; 
	
	return 0;
}

2.二元谓词

#include<bits/stdc++.h>
using namespace std;

class cmp
{
public:
	bool operator()(int v1,int v2)
	{
		return v1 > v2;
	}
};

int main()
{
	vector<int> v;
	v.push_back(7);
	v.push_back(9);
	v.push_back(5);
	v.push_back(100);
	v.push_back(3);
	
	sort(v.begin(),v.end());
	
	for(vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << ' ';
	}
	cout << endl;
	
	sort(v.begin(),v.end(),cmp());
	
	cout << "------------------" << endl;
	
	for(vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << ' ';
	}
	
	return 0;
}

3.内建函数对象

1.算术仿函数

#include<bits/stdc++.h>
using namespace std;

int main()
{
	//取反仿函数
	negate<int> n;
	
	cout << n(50) << endl;
	//对50取反
	
	plus<int> p;
	//加法仿函数，传int类型的数进去相加
	
	cout << p(33,23) << endl;
	return 0;
}

 

2.关系仿函数 

#include<bits/stdc++.h>
using namespace std;

int main()
{
	vector<int> v;
	v.push_back(7);
	v.push_back(9);
	v.push_back(5);
	v.push_back(100);
	v.push_back(3);
	
	sort(v.begin(),v.end());
	
	for(vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << ' ';
	}
	cout << endl;
	
	sort(v.begin(),v.end(),greater<int>());
	
	cout << "------------------" << endl;
	
	for(vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << ' ';
	}
	
	return 0;
}

 

3.逻辑仿函数

#include<bits/stdc++.h>
using namespace std;

int main()
{
	vector<bool> v;
	v.push_back(1);
	v.push_back(1);
	v.push_back(0);
	v.push_back(0);
	v.push_back(1);
	
	for(vector<bool>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << ' ';
	}
	cout << endl;
	
	//将容器v搬到容器v1并且用logical_not进行取反的操作
	vector<bool> v1;
	v1.resize(v.size());
	
	transform(v.begin(),v.end(),v1.begin(),logical_not<bool>());
	
	for(vector<bool>::iterator it = v1.begin(); it != v1.end(); it++)
	{
		cout << *it << ' ';
	}
	cout << endl;
	
	return 0;
}