c语言 结构体动态创建

#include<stdio.h>
#include<malloc.h>
struct Student
{
    int num;  //学号
    int total; //总分
    char name[20]; //姓名
    float score[3]; //3个课目的分数
};

int main()
{
    int N,i,j;
    printf("Please input N:");
    scanf("%d",&N);
    struct Student *stu = NULL;
    stu = (struct Student*)malloc(sizeof(struct Student)*N); //创建一个结构体含有N个数据
    for(i = 0; i < N; i++)
    {
        stu[i].total = 0;
        printf("Please input the No%d student's number:",i+1);
        scanf("%d",&stu[i].num);
        printf("Please input the No%d student's name:",i+1);
        scanf("%s",stu[i].name);
        for(j = 0; j < 3; j++)
        {
            stu[i].score[j] = 0.0; //初始化float 老版本编译器如果不初始化可能会报错
            printf("Please input the No%d student' score of %d:",i+1,j+1);
            scanf("%f",&stu[i].score[j]);
               stu[i].total = stu[i].total + (int)stu[i].score[j];  //求总分
        }
    }
    for(i = 0; i < N; i++)
    {
        if(stu[i].total >= 240) //求总分大于240的
        {
            printf("%d %s\n",stu[i].num,stu[i].name);
        }
    }
    for(i = 0; i < N; i++)
    {
        for(j = 0; j < 3; j++)
        {
            if(stu[i].score[j] < 60) //求科目小于60的
            {
               printf("%d %s %.2f\n",stu[i].num,stu[i].name,stu[i].score[j]);
            }
        }
    //    printf(" %d \n",stu[i].total);
    }
    free(stu); //释放
    return 0;
}