标签：style blog http color io os ar for sp
【本文链接】
http://www.cnblogs.com/hellogiser/p/function-passing-pointer-interview-questions.html
【代码1】
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/*
version: 1.0 author: hellogiser blog: http://www.cnblogs.com/hellogiser date: 2014/10/8 */ #include "stdafx.h" #include <iostream> using namespace std; void GetMemory(char *p) { p = (char *)malloc(100); } void Test(void) { char *str = NULL; GetMemory(str); strcpy(str, "helloworld"); //str=NULL (RUNTIME ERROR) printf(str); } int main() { Test(); return 0; } |
程序崩溃。因为GetMemory并不能传递动态内存，Test函数中的str一直都是NULL。strcpy(str,"helloworld");将使程序崩溃。
【代码2】
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/*
version: 1.0 author: hellogiser blog: http://www.cnblogs.com/hellogiser date: 2014/10/8 */ #include "stdafx.h" #include <iostream> using namespace std; char *GetMemory(void) { char p[] = "helloworld"; return p; // on stack } void Test(void) { char *str = NULL; str = GetMemory(); printf(str); //OK but ??? } int main() { Test(); return 0; } |
可能是乱码。因为GetMemory返回的是指向“栈内存”的指针，该指针的地址不是NULL，但其原先的内容已经被清除，新内容不可知。
【代码3】
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/*
version: 1.0 author: hellogiser blog: http://www.cnblogs.com/hellogiser date: 2014/10/8 */ #include "stdafx.h" #include <iostream> using namespace std; void GetMemory(char **p, int num) { *p = (char *)malloc(num); } void Test(void) { char *str = NULL; GetMemory(&str, 100); strcpy(str, "hello"); printf(str); //ok, output hello } int main() { Test(); return 0; } |
能够输出hello,但是内存泄漏
标签：style blog http color io os ar for sp
原文地址：http://www.cnblogs.com/hellogiser/p/function-passing-pointer-interview-questions.html
