07跨函数使用内存问题

跨函数使用内存

# include<stdio.h>
int f();
int main(void)
{
    int i = 10;
    i = f();
    print("i = %d\n", i);
    
    return 0;
}
int f()
{
    int j = 20;
    return j;
}

Java中的new()

A aa = new A();
//实质上为C语言：
//A *pa = (A *)malloc(sizeof(A));
//free(pa)

注意：因为Java全采用new()所以说能自动释放内存，更安全。

例子2:输入学生数据和输出学生数据

# include<stdio.h>
struct Student
{
    int sid;
    int age;
};
struct Student *CreateStudent(viod);//函数声明
int main(void)                      //void代表主函数不需要传入参数
{
    struct Student * ps;
    ps = CreateStudent();
    ShowStudent(ps);
    
    return 0;
}
void ShowStudent(struct Student *pst)
{
    printf("%d %d\n", pst->sid, pst->age);
}

struct Student * CreateStudent(void)
{
    struct Student * p = (struct Student *)malloc(sizeof(struct Student));
    p->sid = 99;
    p->age = 120;
    return p;
}