传智播客 C/C++学习笔记 指针2 间接赋值是指针存在的最大意义

 

 

 

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <iostream>
using namespace  std;

int getMem3(char** myp1, int *mylen1, char** myp2, int* mylen2)
{
	int ret = 0;
	char *tmp1;
	char* tmp2;

	tmp1 = (char*)malloc(100);
	strcpy(tmp1, "hello");

	*mylen1 = strlen(tmp1);
	*myp1 = tmp1;

	tmp2 = (char*)malloc(100);
	strcpy(tmp2, "python");

	*mylen2 = strlen(tmp2);
	*myp2 = tmp2;  //二级指针的赋值形式
	//myp2 = &tmp2;//如果这样值会是空的
	//这样只是把tmp2指针的地址给了myp2，赋值则要指针解引

	return ret;
}


int main()
{
	int ret = 0;
	char *p1 = NULL;
	int len1 = 0;
	char* p2 = NULL;
	int len2 = 0;

	ret = getMem3(&p1, &len1, &p2, &len2);
	if (ret != 0)
	{
		printf("error %d\n", ret);
		return ret;
	}

	printf("p1 is %s\n", p1);
	printf("p2 is %s\n", p2);

	if (p1 != NULL)
	{
		free(p1);
		p1 = NULL;
	}

	if (p2 != NULL)
	{
		free(p2);
		p2 = NULL;
	}
	printf("len1 is %d\n", len1);
	printf("len2 is %d\n", len2);

	getchar();
	return 1;
}

把1，2，3写在同一个函数里面。