它是很好的做法,以释放在C中的NULL指针? [英] Is it good practice to free a NULL pointer in C?
问题描述
可能重复:结果
是否免费(PTR)其中PTR为NULL损坏内存?
块引用>我正在写释放的指针,如果它是
的malloc()
版的C函数。指针可以是NULL(在发生错误和code没有得到任何分配机会的情况下)或分配的malloc()
。是安全的使用免费(PTR);
而不是如果(PTR!= NULL)免费(PTR);
?
GCC
不抱怨可言,甚至与-Wall -Wextra -ansi -pedantic
,但它好的做法呢?解决方案从的ISO-IEC 9899 :
无效免费(无效* PTR);
如果
PTR
是一个空指针时,没有采取行动。
块引用>不检查
NULL
,它只是增加了更多的虚拟code阅读,因此是一个不好的做法。但是,必须的总是使用时,检查
NULL
指针的malloc
&安培;合。在这种情况下,NULL
意味着出事了,很有可能是没有内存可用。Possible Duplicate:
Does free(ptr) where ptr is NULL corrupt memory?I'm writing a C function that frees a pointer if it was
malloc()
ed. The pointer can either be NULL (in the case that an error occured and the code didn't get the chance to allocate anything) or allocated withmalloc()
. Is it safe to usefree(ptr);
instead ofif (ptr != NULL) free(ptr);
?
gcc
doesn't complain at all, even with-Wall -Wextra -ansi -pedantic
, but is it good practice?解决方案Quoting the C standard, 7.20.3.2/2 from ISO-IEC 9899:
void free(void *ptr);
If
ptr
is a null pointer, no action occurs.Don't check for
NULL
, it only adds more dummy code to read and is thus a bad practice.
However, you must always check for
NULL
pointers when usingmalloc
& co. In that caseNULL
mean that something went wrong, most likely that no memory was available.这篇关于它是很好的做法,以释放在C中的NULL指针?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!