malloc之跨函数使用内存

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

struct Student{
    int sid;
    int age;
};

struct Student * CreateStudent();
void ShowStudent(struct Student *);

int main()
{
    struct Student *ps;
    ps = CreateStudent();
//    free(ps);
    ShowStudent(ps);
    free(ps);
    return 0;
}

struct Student * CreateStudent()
{
    struct Student * p = (struct Student *)malloc(sizeof(struct Student));
    p->age = 88;
    p->sid = 99;
//    free(p);
    return p;
}

void ShowStudent(struct Student *pst)
{
    printf("%d %d\n",pst->sid,pst->age);
}