给出如下结构体,要求全部在堆区开辟空间。有多个老师,每个老师有多个学生。
typedef struct
{
char *name;//老师
int stu_num;//学生数
char **stu_arr;//学生名字
}TEACHER;
需要注意以下问题:
- 此问题使用双层循环即可解决。
- 外层循环处理这三个成员变量:给name开辟空间;给stu_num赋值;给stu_arr开辟5个连续的保存一级地址地char**类型的空间。即给成员变量赋值。
- 在内层循环中使用stu_arr5个char*类型的空间开辟,每个均开辟5个char*类型的空间,再给他们赋值。当然,这个过程(内层循环)要执行25次。即给二级地址中引用的一级地址开辟空间并赋值。
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef struct
{
char *name;
int stu_num;
char **stu_arr;
}TEACHER;
int main(int argc, char *argv[])
{
TEACHER **teachers = (TEACHER **)calloc(5, sizeof(TEACHER));
for (int i = 0; i < 5; i++)
{
//*name
teachers[i] = (TEACHER*)calloc(1, sizeof(TEACHER));
teachers[i]->name = (char *)calloc(32, sizeof(char));
strcpy(teachers[i]->name, "lao_shi");
printf("%s\n", teachers[i]->name);
//stu_num
teachers[i]->stu_num = 3;
printf("%d\n", teachers[i]->stu_num);
//**stu_arr
teachers[i]->stu_arr = (char **)calloc(5, sizeof(char *));
printf("%p\n", teachers[i]->stu_arr);
for (int j = 0; j < 5; j++)
{
//*stu_arr
teachers[i]->stu_arr[j] = (char *)calloc(teachers[i]->stu_num, 128 * sizeof(char));
strcpy(teachers[i]->stu_arr[j], "xiao_ming");
printf("%s\n", teachers[i]->stu_arr[j]);
}
}
//释放
for (int i = 0; i < 5; i++)
for (int j = 0; j < 5; j++)
if (teachers[i]->stu_arr[j]) free(teachers[i]->stu_arr[j]), teachers[i]->stu_arr[j] = NULL;
for (int i = 0; i < 5; i++) if (teachers[i]) free(teachers[i]), teachers[i] = NULL;
if (teachers) free(teachers), teachers = NULL;
system("pause");
return 0;
}