#include<cstdio>          'cstdio' file not found
#include<algorithm>
using namespace std;
int main(){
    const int n=6;
    int a[6]={5,12,7,2,9,3};
    sort(a,a+n);//对数组a进行排序
    for(int i=0;i<n;i++){
        printf("%d ",a[i]);
    }
    return 0;}

Thanks.