·包含头文件<algorithm>
升序：sort(begin,end,less<data-type>());
降序：sort(begin,end,greater<data-type>());
·整型数组排序 demo

int main () {
      int a[10]={2,4,1,23,5,76,0,43,24,65};
      for(int i=0;i<20;i++)
          cout<<a[i]<<endl;
      sort(a,a+20,greater<int>());  
      for(i=0;i<10;i++)
          cout<<a[i]<<endl;
      return 0;
}

·字符串中字符排序 demo

int stringSort(string str, char *chars) {
    sort(str.begin(), str.end());
    for (int i = 0; i < str.length(); i++)
        chars[i] = str[i];
    return 0;
}

·结构体排序 demo

#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
typedef struct {
    int a,b;
}link;
bool cmp(link x,link y) {
    if(x.a==y.a)
        return x.b>y.b;
    return x.a>y.a;
}
int main() {
    link x[4];
    for(int i=0;i<4;i++)
        cin>>x[i].a>>x[i].b;
    sort(x,x+4,cmp);
    for(int i=0;i<4;i++)
        cout<<x[i].a<<' '<<x[i].b<<endl;
    return 0;
 }