sort函数请教！

[xiaolai1012]

#include <iostream>
#include <algorithm>

using namespace std;

bool compare(int a,int b)
{
      return a>=b;   //这里为啥不能用>=或<=或==,一用就出错！！！
}
int main()
{
     int a[20]={2,4,1,23,5,76,0,43,24,65},i;
     for(i=0;i<20;i++)
       cout<<a[i]<<endl;
     sort(a,a+20,compare);
     for(i=0;i<20;i++)
       cout<<a[i]<<endl;
     return 0;
}

[relive007]

(a>b) || (a==b)

[delphiwcdj]

The sort algorithm sorts the elements in the range [start,end) into ascending order. If two elements are equal, there is no guarantee what order they will be in.

[delphiwcdj]

#include <iostream>
#include <algorithm>
using namespace std;
bool compare(int a,int b)
{
	return (a>=b); // ok
}
int main()
{
	int a[10]={2,4,1,23,5,76,0,43,24,65},i;
	sort(a,a+10,compare);
	for(i=0;i<10;i++)
		cout<<a[i]<<endl;
	return 0;
}

[delphiwcdj]

当数组a里有相同的元素时，compare中不能有==
当数组a里没有相同的元素时，compare可以有==

[relive007]

不好意思，我说错了。