C二级指针分配内存方式与释放

#define  _CRT_SECURE_NO_WARNINGS 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

//通过函数返回值返回开辟的内存首地址
char **getMem(int num)
{
	int i = 0;
	char **p2 = NULL;
	p2 = (char **)malloc(sizeof(char *) * num);
	if (p2 == NULL)
	{
		return NULL;
	}

	for (i=0; i<num; i++)
	{
		p2[i] = (char *)malloc(sizeof(char)  * 100  ); //char buf[100];
		sprintf(p2[i], "%d%d%d", i+1, i+1, i+1);
	}
	
	return p2;
}

//通过三级指针动态打造二维数组
int getMem1(char ***p3, int num)
{
	int i = 0;
	char **tmp = NULL;

	if (p3 == NULL)
	{
		return -1;
	}
	
	tmp = (char **)malloc(sizeof(char *) * num);
	if (tmp == NULL)
	{
		return -2;
	}

	for (i=0; i<num; i++)
	{
		tmp[i] = (char *)malloc(sizeof(char)  * 100  ); //char buf[100];
		sprintf(tmp[i], "%d%d%d", i+1, i+1, i+1);
	}
	
	*p3 = tmp;		//间接赋值是指针存在的最大意义 

	return 0;
}

void getMem_Free(char ***p3 , int num)
{
	int i = 0;
	char **tmp = NULL;

	if (p3 == NULL)
	{
		return ;
	}
	tmp = *p3; 

	for (i=0; i<num; i++)
	{
		free(tmp[i]);
	}
	free(tmp);
	 
	*p3 = NULL; //把实参赋值成null
}

int main(int argc, const char * argv[])
{
	int i = 0, j = 0;
	char **p2 = NULL;
	int num = 5;
	char *tmp = NULL;
	char tmpbuf[100];

	p2 = getMem(num);
	
	for (i=0; i<num; i++)
	{
		printf("%s \n", p2[i]);
	}

	getMem_Free(&p2, num);
	puts("888888888888888888888888888888888888888888");

	getMem1(&p2, num);

	for (i=0; i<num; i++)
	{
		printf("%s \n", p2[i]);
	}

	getMem_Free(&p2, num);

	return 0;
}

测试结果