calloc（1,1）vs. * malloc（1）= 0 [英] calloc(1,1) vs. *malloc(1)=0
问题描述
要组成一个正确动态分配的空C字符串，是否足够
说：
返回calloc（1,1）;
或我最好使用更长的版本
char * p = malloc（1）;
if（ p）* p = 0;
返回p;
？ TIA
To make up a proper dynamically allocated empty C string, would it suffice to
say:
return calloc(1, 1);
or am I better off using the longer version
char *p = malloc(1);
if (p) *p = 0;
return p;
? TIA
推荐答案
rihad< ri *** @ mail.ru>写道：
rihad <ri***@mail.ru> wrote:
要组成一个正确动态分配的空C字符串，是否足以说：
返回calloc（1,1） ;
或者我最好使用更长的版本
char * p = malloc（1）;
if（p）* p = 0;
return p;
To make up a proper dynamically allocated empty C string, would it suffice to
say:
return calloc(1, 1);
or am I better off using the longer version
char *p = malloc(1);
if (p) *p = 0;
return p;
两个版本都可能返回NULL，这不是指向空的
字符串的指针。除非你希望函数的调用者检查
NULL，否则你应该在返回p之前采取适当的行动。
至于calloc：我总是很有趣感觉这个空间
初始化为所有位零行为。当你处理未签名的角色权利时，这不是一个问题
，但可能有b $ b令人惊讶的结果。 （引用C理由）使用
其他类型时。因此，我完全不使用它。
HTH
问候
-
Irrwahn
（ir*******@freenet.de）
Both versions may return NULL, which is not a pointer to an empty
string. Unless you expect the caller of your function to check for
NULL you should take appropriate action before returning p.
As for calloc: I always have a funny feeling about this "the space
is initialized to all bits zero" behaviour. That isn''t a problem
when you''re dealing with unsigned character entitities, but may have
"astonishing results" (to quote the C Rationale) when working with
other types. Thus I stay away from using it at all.
HTH
Regards
--
Irrwahn
(ir*******@freenet.de)
" rihad" < RI *** @ mail.ru>在消息中写道
新闻：ai ******************************** @ 4ax.com ...
"rihad" <ri***@mail.ru> wrote in message
news:ai********************************@4ax.com...
要构成一个正确动态分配的空C字符串，是否足以说
：
返回calloc（1,1）;
或者我最好使用更长的版本
char * p = malloc（1）;
if（p）* p = 0;
返回p;
To make up a proper dynamically allocated empty C string, would it suffice to say:
return calloc(1, 1);
or am I better off using the longer version
char *p = malloc(1);
if (p) *p = 0;
return p;
这两者之间没有区别，来自C'的POV。
< OT>出于兴趣，你为什么要做这样的事情？ :-)< / OT>
There is no difference between those two, from C''s POV.
<OT> Just out of interest, why would you want to do such a thing? :-) </OT>
" rihad" < RI *** @ mail.ru>在消息中写道
新闻：ai ******************************** @ 4ax.com ...
"rihad" <ri***@mail.ru> wrote in message
news:ai********************************@4ax.com...
要构成一个正确动态分配的空C字符串，是否足以说
：
返回calloc（1,1）;
或者我最好使用更长的版本
char * p = malloc（1）;
if（p）* p = 0;
返回p;
To make up a proper dynamically allocated empty C string, would it suffice to say:
return calloc(1, 1);
or am I better off using the longer version
char *p = malloc(1);
if (p) *p = 0;
return p;
这两者之间没有区别，来自C'的POV。
< OT>出于兴趣，你为什么要做这样的事情？ :-)< / OT>
There is no difference between those two, from C''s POV.
<OT> Just out of interest, why would you want to do such a thing? :-) </OT>
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