c - C语言中指针的使用

Question

当我运行此代码时，它返回 Segmentation Fault (core dumped) .我尝试了很多东西，但我相信我使用的指针是错误的。我究竟做错了什么？

要求:每个变量都必须是一个指针。

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

int main() { 
    /* All the variables that needed to be defined */ 
    int *i = malloc(sizeof(int)); 
    int *number = malloc(sizeof(int)); 
    int *failing_count = malloc(sizeof(int)); 
    double *total = malloc(sizeof(double)); 
    double *grade = malloc(sizeof(double)); 

    failing_count = 0; 
    total = 0; 
    grade = 0; 

    /* User is asked to enter the number of grades that are received */ 
    printf("Enter number of grades:\n "); 
    scanf("%d", number);     

    /* For Loop is run */ 
    for (*i = 0; i < number; *i++) { 
        printf("Enter a grade:\n "); 
        scanf("%lf", grade); 

        if (*grade < 70) {
            failing_count++; 
        } 
        *total = *total + *grade; 
    }        

    /* Program prints the results */ 
    printf("Average grade is %lf\n", *total / *number); 
    printf("Number of failing grades is %d\n", failing_count); 
    return 0; 

    free(i); 
    free(number); 
    free(failing_count); 
    free(total); 
    free(grade); 
}

Answer 1

使用 *在任何地方你想使用所指向的值而不是指针。

改变:

        failing_count = 0; 
        total = 0; 
        grade = 0; 

到:

        *failing_count = 0; 
        *total = 0; 
        *grade = 0; 

改变:

        for(*i = 0; i<number; *i++){ 

到:

        for(*i = 0; *i<*number; (*i)++){ 

改变:

                        failing_count++; 

到:

                        (*failing_count)++; 

改变:

        printf("Number of failing grades is %d\n", failing_count); 

到:

        printf("Number of failing grades is %d\n", *failing_count); 

在:

        return 0; 

        free(i); 
        free(number); 
        free(failing_count); 
        free(total); 
        free(grade); 

return 后面的语句永远不会被执行。移动 return最后。