帮助c指针 [英] Help in c pointers
问题描述
HI
int * p;
* p = 4;
char * msg;
* msg =''c'';
printf（" msg is％s"，msg）;
当我尝试传递值4来放置整数指针p指向
它说seg错误
但是对于char指针它工作正常。
为什么会出现这种情况
帮助
HI
int *p;
*p = 4;
char * msg;
*msg = ''c'';
printf("msg is %s",msg);
when i try to pass a value 4 to place what integer pointer p points to
it says seg fault
but for the char pointer it works fine.
Why this behaviour
Help
推荐答案
ma *********** @ gmail.com schrieb：
ma***********@gmail.com schrieb:
int * p;
* p = 4;
int *p;
*p = 4;
使用指针时你已经完成了greates编程错误。
当它指向某个地方时不要使用指针！
最好试试这个：
int * p;
p =（int *）malloc（sizeof（int））;
* p = 4;
You have done the greates programming fault when using pointers.
Never use a pointer when it points somewhere!
Better try this:
int * p;
p = (int *) malloc (sizeof(int));
*p = 4;
Thanx快速回复。
在这里我担心为什么在使用char *时我能够传递价值
给它。即使这指向某个地方也是正确的。
所以当使用int *指向somwhere我无法传递价值
但它使用char *我能够做到这一点。为什么???
提前预付
Thanx for the quick reply.
In here i am concerned why while using char * i am able to pass value
to it. Even this points to somewhere right.
So while using int * which points somwhere i am not able to pass value
to it but while using the char * i am able to do it . Why???
Thanx in advance
" Zero" < CH ******** @ web.de>在新闻中写道：1141121017.828706.126940
@ e56g2000cwe.googlegroups.com：
"Zero" <ch********@web.de> wrote in news:1141121017.828706.126940
@e56g2000cwe.googlegroups.com:
ma *********** @ gmail.com schrieb：
ma***********@gmail.com schrieb:
int * p;
* p = 4;
使用指针时你已经完成了greates编程错误。
当它指向某个地方时不要使用指针！
int *p;
*p = 4;
You have done the greates programming fault when using pointers.
Never use a pointer when it points somewhere!
ITYM：如果它没有*指向任何地方，就不要使用指针（也就是说，
从不使用未初始化的指针。
最好试试这个：
int * p;
p =（int *）malloc（sizeof（int））;
* p = 4;
ITYM: Never use a pointer if it does *not* point to anywhere (that is,
never use an uninitialized pointer.
Better try this:
int * p;
p = (int *) malloc (sizeof(int));
*p = 4;
最好不要。没有必要强制转换malloc的返回值，并且这样做可以隐藏错误。总是，是*总是*，检查malloc
成功：
int * p = malloc（sizeof * p）;
if（p）{
* p = 4;
}否则{
/ *句柄错误* /
}
思南
-
A. Sinan Unur< 1u ** @ llenroc.ude.invalid>
（反转每个组件并删除.invalid for email address）
comp.lang.perl.misc关于WWW的指南：
http://mail.augustmail.com/~tadmc/cl...uidelines.html
Better not. There is no need to cast the return value of malloc, and
doing so can hide errors. Always, yes *always*, check that malloc
succeeded:
int *p = malloc(sizeof *p);
if ( p ) {
*p = 4;
} else {
/* handle error */
}
Sinan
--
A. Sinan Unur <1u**@llenroc.ude.invalid>
(reverse each component and remove .invalid for email address)
comp.lang.perl.misc guidelines on the WWW:
http://mail.augustmail.com/~tadmc/cl...uidelines.html
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