利用qsort给结构体按三级排序

#include <stdio.h>
#include<stdlib.h>
#include<string.h>

typedef struct{
    int id;
    char name[20];
    int age;
}Staff,*snode;

int cpr(const void * a,const void* b)
{
    snode x = (snode) a;
    snode y = (snode) b;
    if(x->age != y->age)
        return x->age - y->age;
    else if(x->id != y->id)
        return x->id - y->id;
    else
        return strcmp(x->name,y->name);
}
int main()
{
    int n;
    scanf("%d",&n);
    int min = n>3?3:n;
    snode s = (snode)malloc(sizeof(Staff)*n);
    for(snode i = s;i<s+n;i++)
        scanf("%d %s %d",&i->id,i->name,&i->age);
    qsort(s,n,sizeof(s[0]),cpr);

    for(snode i= s;i<s+min;i++)
        printf("%d %s %d\n",i->id,i->name,i->age);
    return 0;
}