指针间接赋值

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

/*间接赋值成立的三个条件：

条件一：//定义一个实参　　//定义一个形参

条件二：//建立关联：把实参取地址传给形参

条件三：//形参间接去修改实参的值

*/

/*

　　用n级指针形参，去间接的修改n-1级指针（实参）的值。

*/

/*间接赋值的场景

//1 2 3 这3个条件 写在有一个函数
//12 写在一块 3 单独写在另外一个函数里面 =====>函数调用
//1 23写在一块

void main()

{

　　

char from[128];
char to[128] = {0};
char *p1 = from;
char *p2 = to;

strcpy(from, "1122233133332fafdsafas");

while (*p1 != '')
{
*p2 = *p1;
p2 ++;
p1++;
}

printf("to:%s 
", to);

　

}

*/


int getMem3(char **myp1, int *mylen1, char **myp2, int *mylen2)
{
int ret = 0;
char *tmp1, *tmp2;
tmp1 = (char*)malloc(100);
strcpy(tmp1, "1234456789");
*mylen1 = strlen(tmp1);    //1级指针
*myp1 = tmp1;    //2级指针的间接赋值


tmp2 = (char*)malloc(200);
strcpy(tmp2, "abcdefghigklmn");
*mylen2 = strlen(tmp2);//1级指针
*myp2 = tmp2;//2级指针的间接赋值
return ret;
}

int main()
{
char *p1 = NULL;
char *p2 = NULL;
int len1 = 0;
int len2 = 0;
int ret = getMem3(&p1,&len1,&p2,&len2);
if (ret !=0){
printf("func getMem3 %d",ret);
return ret;
}
printf("p1:%s
", p1);
printf("p2:%s
", p2);
if (p1 != NULL)
{
free(p1);
p1 = NULL;
}
if (p2 != NULL)
{
free(p2);
p2 = NULL;
}
system("pause");
return 0;
}