c语言编程，程序编译没错，运行弹出debug，问题在排序模块，把主函数的排序注释掉后不会弹出debug

Question

# ##

# include <stdio.h>
# include <malloc.h>

void input(struct student * stu, int val);
void paixu(struct student * stu, int val);
void output(struct student * stu, int val);

struct student 
{
    int age;
    char name[100];
    float score;
};

int main(void)
{
    int val;
    printf("请输入学生总数：\n");
    scanf("%d", &val);
    float a = 3.0/10;

    struct student * stu = (struct student *)malloc(val*sizeof(struct student *));//分配val个struct student *型动态内存

    input(stu, val);//调用输入学生数据的函数

    paixu(stu, val);//调用按成绩排序的函数

    output(stu, val);//调用输出学生数据的函数

    free(stu);//释放学生数据所占用的内存

    return 0;
}


void input(struct student *stu, int val)
{
    int i;

    for(i = 0; i < val; ++i)
    {
        printf("请输入第%d个学生的信息\n",i+1);

        printf("年龄：");
        scanf("%d", &stu[i].age);

        printf("姓名：");
        scanf("%s", &stu[i].name);

        printf("分数：");
        scanf("%f",&stu[i].score);
    }
    return;
}

void paixu(struct student *stu, int val)
{
    int i;
    int j;
    struct student st;

    for(i = 0; i < val-1; ++i)//按成绩升序排序
    {
        for(j = 0; j < val-1-i; ++j)

            if(stu[j].score > stu[j+1].score)
            {
                st = stu[j];
                stu[j] = stu[j+1];
                stu[j+1] = st;
            }

    }
    return;
}

void output(struct student *stu, int val)
{
    int i;

    for(i = 0; i < val; ++i)
    {
        printf("第%d个学生的信息为：\n", i+1);

        printf("年龄：%d 姓名：%s 成绩：%f \n", stu[i].age, stu[i].name, stu[i].score);
    }
    return;
}

Answer 1

struct student * stu = (struct student *)malloc(val*sizeof(struct student ));分配val个student结构体大小内存