#include "stdio.h"
#include "stdlib.h"
struct courses
{
    int programming;
    int database;
    int network;
    double score;
    int level;
    scanf("%lf",&score);
        if (score>300||score<0) //300分如何计算及格分来评定等级               还有这个if结构不知道哪里错了
         {
           printf("成绩输入错误！\n");
         }
    else
        {
          level=(int)((score-180)/10);
          switch(level)
                {
                 case 1: printf("优\n");break;
                 case 2: printf("优\n");break;
                 case 3: printf("良\n");break;
                 case 4: printf("中\n");break;
                 case 5: printf("差\n");break;
                 default: printf("劣\n");break;
                }
        }
};
struct student
{
    int num;       //学号
    char name[10]; //姓名
    int sum;       //总分
    struct courses sc[3];
};
void sumScore(struct student students[])
{
    int i;
    for (i = 0; i < 3; i++)
       {
         students[i].sum=students[i].sc[0].programming+students[i].sc[1].network+students[i].sc[2].database;
       }
}
int main()
{
    struct student students[5];//3名同学
    int i;
    for (i = 0; i < 3; i++)
       {
            printf("num:");
            scanf("%d",&students[i].num);
            printf("name:");
            scanf("%s",students[i].name);
            printf("programming score:");
            scanf("%d",&students[i].sc[0].programming);
            printf("network score:");
            scanf("%d",&students[i].sc[1].network);
            printf("database score:");
            scanf("%d",&students[i].sc[2].database);
        }
    sumScore(students);
    printf("num\tname\tsum\n");
    for (i = 0; i < 3; i++)
       {
        printf("%d\t%s\t%d\n",students[i].num,students[i].name,students[i].sum);
       }
      
    return 0;
}

struct里面还能放代码，涨见识了

谢谢，那300分做为总分应该怎么做等级评定呢

÷60

我改了，但是想满足3名学生的他三科总分以及评定就比如100分
printf("请输入成绩:\n");
      scanf("%lf",&score);
    if (score>100||score<0){
        printf("成绩输入错误！\n");
}
    else
    {
        level=(int)((score-50)/10);
        switch(level)
        {
        case 5: printf("优\n");break;
        case 4: printf("优\n");break;
        case 3: printf("良\n");break;
        case 2: printf("中\n");break;
        case 1: printf("差\n");break;
        default: printf("劣\n");break;
        }
     }
那300分呢

看你分几档
要是分⑤档0---60    60--120   120---180    180--240    240---300
要是分⑥档那就50间隔

数学不太好，这串代码是要满足该咋写：level=(int)((score-50)/10);//就是该除多少才能满足

：level=(int)(score/50）或者60

改完了，还有一个问题就是我需要入三名同学三科总成绩以及评等级但是我这么写只能一名同学成绩

放全部代码