这是一个用free（）释放内存的正确方法 [英] IS this a proper way of freeing memory with free()
问题描述
大家好，
这是一个小代码，
int main（无效）
{
char * p =（char *）malloc（100）;
strcpy（p，" Test1234567890"）;
p = p + 10;
免费（p）;
/ ***这里是内存泄漏，因为p现在是
指向10位置过去分配内存的开始
**** /
/ **再加一些p的东西** /
< br $>
}
谢谢和问候，
Raman Chalotra
Hi All,
Here is a small Code,
int main(void)
{
char *p=(char *) malloc(100);
strcpy(p,"Test1234567890");
p=p+10;
free(p);
/*** Is here a memory Leak, because p is now
pointing 10 location past to the start of allocated memory
****/
/** some stuff with p again**/
}
Thanks and Regards,
Raman Chalotra
推荐答案
拉曼写道：
Raman wrote:
大家好，
这是一个小代码，
int main（无效）
{
char * p =（char *）malloc（100）;
Hi All,
Here is a small Code,
int main(void)
{
char *p=(char *) malloc(100);
这里必须有多少次人们不得不说不要将返还的价值转换为
malloc的价值？有没有人在发布之前阅读档案？
How many times must people here have to say "do not cast the return
value of malloc"? Does anyone read the archive before they post?
strcpy（p，" Test1234567890"）;
p = p + 10;
免费（p）;
/ ***这里是内存泄漏，因为p现在是
指向10位置过去到分配的开始记忆
**** /
strcpy(p,"Test1234567890");
p=p+10;
free(p);
/*** Is here a memory Leak, because p is now
pointing 10 location past to the start of allocated memory
****/
这是完全未定义的行为。你的厕所可能会爆炸。不要
这样做。
-
Ian Collins。
It''s completely undefined behaviour. Your toilet might explode. Don''t
do it.
--
Ian Collins.
Raman写道：
Raman wrote:
char * p =（char *）malloc（100）;
char *p=(char *) malloc(100);
char * p = malloc（100 * sizeof * p）;
不要投出返回值malloc（）。
char *p = malloc(100 * sizeof *p);
Don''t cast the return value from malloc().
strcpy（p，" Test1234567890"）;
p = p + 10;
免费（p）;
/ ***这里有一个内存泄漏，因为p现在是
指向10位置过去到分配内存的开始
**** /
strcpy(p,"Test1234567890");
p=p+10;
free(p);
/*** Is here a memory Leak, because p is now
pointing 10 location past to the start of allocated memory
****/
完全无效。 free（）期望一个指针最初从
之一返回其他分配函数（calloc，malloc，realloc）。
NAME
免费分配内存
简介
#include< stdlib.h>
无空（void * ptr）;
描述
free（）函数将导致ptr指向的空间为
释放;也就是说，可供进一步分配。如果ptr是null
指针，则不会发生任何动作。否则，如果参数与之前由calloc（），malloc（）或realloc（）函数返回的
指针不匹配，或者
如果空间已经通过调用free（）或realloc（）解除分配，
行为未定义。
任何使用引用释放空间的指针都会导致undefined
行为。
Completely invalid. free() expects a pointer originally returned from one of
the other allocation functions (calloc, malloc, realloc).
NAME
free - free allocated memory
SYNOPSIS
#include <stdlib.h>
void free(void *ptr);
DESCRIPTION
The free() function shall cause the space pointed to by ptr to be
deallocated; that is, made available for further allocation. If ptr is a null
pointer, no action shall occur. Otherwise, if the argument does not match a
pointer earlier returned by the calloc(), malloc(), or realloc() function, or
if the space has been deallocated by a call to free() or realloc(), the
behavior is undefined.
Any use of a pointer that refers to freed space results in undefined
behavior.
Ian Collins写道：
Ian Collins wrote:
> char * p =（char *）malloc（100）;
> char *p=(char *) malloc(100);
这里必须有多少次人们不得不说不要投出返还给malloc的
值？有没有人在发布之前阅读档案？
How many times must people here have to say "do not cast the return
value of malloc"? Does anyone read the archive before they post?
基本上永远。只要它仍然在人们阅读的书中 - 他们就会继续这样做。
Basically forever. As long as it''s still in books that people read - they''ll
keep doing it.
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