程序代码：

#include <stdio.h>

struct Students
    {
        int num;
        int score;
    };
    
void print_under_sixty(struct Stduent *stds,int t)
{
    int i,count;
    printf("================\n");
    printf("name    score\n");
    for(i=1;i<=t;i++)
    {
        if(stds.score[i] < 60)
        {
            count++;
            printf("%d%10d\n",stds[i].num,stds[i].score);
        }
    }
    printf("the count of under sixty : %d\n",count);
}

void main()
{
    int total = 0,i;
        Students std[30];
    for(i=1;i<30;i++)
    {
        printf("student %d ",i);
        std[i].num = i;
        scanf("%d",&std[i].score);
        if(std[i].score < 0)
            break;
        total++;
    }
    printf("num    score\n");
    for(i=1;i<=total;i++)
    {
        printf("%d%10d\n",std[i].num,std[i].score);
    }
    print_under_sixty(std,total);
}