sort函数的第三个参数cmp

sort 函数的第三个参数 cmp

案例1：

#include<iostream>  
#include<algorithm>		//因为用了sort()函数  
#include<functional>	//因为用了greater<int>()  
using namespace std;  
  
void main()  
{  
    int a[]={3,1,4,2,5};  
    int i;  
    int len=sizeof(a)/sizeof(int);//这里切记要除以sizeof(int)!  
  
    sort(a ,a + len, greater<int>());//内置类型的由大到小排序  
    for(i=0;i<len;i++)  
        cout<<a[i]<<" ";  
    cout<<"
";  

    sort(a, a + len, less<int>());        //内置类型的由小到大排序  
    for(i=0;i<len;i++)  
        cout<<a[i]<<" ";  
	system("pause");
} 

案例2：

#include <iostream>
#include<vector>
#include <algorithm> 
using namespace std;  
  
//下面的比较函数的返回值为0或者1   
bool cmp1(int m, int n)  
{  
     return m>n;	//降序排列
}  

bool cmp2(int m, int n)  
{  
     return m<n;	//升序排列
}
int main()  
{  
    int a[10] = {8, 6, 9, 4, 21, 1, 1, 3, 78, -5};  
    sort(a, a+10, cmp1);  

    for (int i=0; i<10; ++i)  
        cout<<a[i]<<" ";  
    cout<<endl<<endl;  
	sort(a, a+10, cmp2);  

    for (int i=0; i<10; ++i)  
        cout<<a[i]<<" ";  
    cout<<endl<<endl;

	stable_sort(a,a+10,cmp1);
	for (int i=0; i<10; ++i)  
        cout<<a[i]<<" ";  
    cout<<endl<<endl;

	stable_sort(a,a+10,cmp2);
	for (int i=0; i<10; ++i)  
        cout<<a[i]<<" ";  
    cout<<endl<<endl;

    system("pause"); 
	return 0;
}