【C语言程序设计第四版】例9-3代码

#include <stdio.h>

struct student{
    int num;
    char name[40];
    int computer, english, math;
    double average;
};
int update_score(struct student *p, int n, int num, int course, int score);

int main(void){
    int course, i , n, num, pos, score;
    struct student students[50];
    
    printf("Input n:");
    scanf("%d", &n);
    for (i = 0; i < n; i++) {
        printf("Input the info of No.%d:
", i+1);
        printf("number:");
        scanf("%d", &students[i].num);
        printf("name:");
        scanf("%s", students[i].name);
        printf("math score:");
        scanf("%d", &students[i].math);
        printf("english score:");
        scanf("%d", &students[i].english);
        printf("computer socre:");
        scanf("%d", &students[i].computer);
        students[i].average = (students[i].math + students[i].english + students[i].computer) / 3.0;
    }
    
    printf("input the number of the student to be updated");
    scanf("%d", &num);
    printf("Choice of course:1.math 2.english 3.computer");
    scanf("%d", &course);
    printf("Input the new sorce");
    scanf("%d", &score);
    
    pos = update_score(students, n, num, course, score);
    
    if (pos == -1) {
        printf("Not found!
");
    }else{
        printf("After update:
");
        printf("num	 math	 english	 computer 
");
        printf("%d	 %d	 %d	 %d
", students[pos].num, students[pos].math, students[pos].english, students[pos].computer);
    }
        
    
    return 0;
}

int update_score(struct student *p, int n, int num, int course, int score){
    int i, pos;
    for (i = 0; i < n; i++, p++) {
        if (p->num == num) break;
        
    }
    if (i < n) {
        switch (course) {
            case 1:
                p ->math = score;
                break;
            case 2:
                p->english = score;
                break;
            case 3:
                p->computer =score;
                break;
        }
        pos = i;
    }else{
        pos = -1;
    }
    
    return pos;
}