C提高_day03_玩转多级指针

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

char **getMem51(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;
}

int getMem52(char ***p3 , int num)
{
int i = 0;
char **tmp = NULL;

if (p3 == NULL)  //判断p3 而不是*p3.  p3指向的内存空间可以是NULL
{
return -1;
}

tmp = (char **)malloc(sizeof(char *) * num);
if (tmp == NULL)
{
return NULL;
}

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;
//1 2

return 0;
}

void getMem52_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
}

void main()
{
int i = 0, j = 0;
char **p2 = NULL;
int num = 5;

//p2 = getMem51(num);

getMem52(&p2, num);

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

getMem52_Free(&p2, num);
printf("hello...\n");
system("pause");
return ;
}