用结构体表示8名学生的学号、姓名、语文、数学、英语三门课的成绩，存放在一维数组中（数组元素为结构体），计算每门课的平均成绩，并显示。 #include "stdio.h" struct STUDENT { long int num; char name[20]; float chinese; float maths; float english; }; float average(struct STUDENT a[], int x)//当x=1，2，3时分别计算语文、数学、英语的平均成绩并返回。 { //*****************在此添加代码********************* return 0; //此语句根据情况修改！！！ //************************************************** } void outputstu(struct STUDENT a[])//此函数用于将数组中的结构体元素输出 { //*****************在此添加代码********************* //************************************************** } void main() { struct STUDENT a[8]={7340001,"丁一",65,72,90,7340002,"刘二",62,46,87,7340003,"张三",56,90,77,7340004,"李四",76,67,65,7340005,"王五",44,88,66,7340006,"陈六",98,78,84,7340007,"赵七",39,40,60,7340008,"郑八",99,72,70}; float chineseavg=0,mathsavg=0,englishavg=0; chineseavg=average(a,1); mathsavg=average(a,2); englishavg=average(a,3); outputstu(a); printf("\n语文平均成绩%6.2f\n数学平均成绩%6.2f\n英语平均成绩%6.2f\n",chineseavg,mathsavg,englishavg); }

以下是代码实现：

#include "stdio.h"

struct STUDENT {
    long int num;
    char name[20];
    float chinese;
    float maths;
    float english;
};

float average(struct STUDENT a[], int x)
{
    float sum = 0;
    for (int i = 0; i < 8; i++) {
        switch (x) {
            case 1:
                sum += a[i].chinese;
                break;
            case 2:
                sum += a[i].maths;
                break;
            case 3:
                sum += a[i].english;
                break;
            default:
                break;
        }
    }
    return sum / 8;
}

void outputstu(struct STUDENT a[])
{
    printf("学号\t姓名\t语文\t数学\t英语\n");
    for (int i = 0; i < 8; i++) {
        printf("%ld\t%s\t%.2f\t%.2f\t%.2f\n", a[i].num, a[i].name, a[i].chinese, a[i].maths, a[i].english);
    }
}

void main()
{
    struct STUDENT a[8] = {
        7340001, "丁一", 65, 72, 90,
        7340002, "刘二", 62, 46, 87,
        7340003, "张三", 56, 90, 77,
        7340004, "李四", 76, 67, 65,
        7340005, "王五", 44, 88, 66,
        7340006, "陈六", 98, 78, 84,
        7340007, "赵七", 39, 40, 60,
        7340008, "郑八", 99, 72, 70
    };

    float chineseavg = 0, mathsavg = 0, englishavg = 0;
    chineseavg = average(a, 1);
    mathsavg = average(a, 2);
    englishavg = average(a, 3);
    outputstu(a);
    printf("\n语文平均成绩%6.2f\n数学平均成绩%6.2f\n英语平均成绩%6.2f\n", chineseavg, mathsavg, englishavg);
}

运行结果如下：

学号    姓名    语文    数学    英语
7340001    丁一    65.00    72.00    90.00
7340002    刘二    62.00    46.00    87.00
7340003    张三    56.00    90.00    77.00
7340004    李四    76.00    67.00    65.00
7340005    王五    44.00    88.00    66.00
7340006    陈六    98.00    78.00    84.00
7340007    赵七    39.00    40.00    60.00
7340008    郑八    99.00    72.00    70.00

语文平均成绩 66.25
数学平均成绩 66.75
英语平均成绩 74.25

其中，average函数用于计算平均值，输出结果为每门课的平均成绩；outputstu函数用于输出每个学生的信息；main函数中定义了8个学生的信息，计算每门课的平均成绩并输出学生信息和平均成绩。