Re: [ROOT] compiler warning

From: Elias Athanasopoulos (
Date: Sun Jun 06 2004 - 15:54:54 MEST

On Sun, Jun 06, 2004 at 07:31:11PM +0200, cstrato wrote:
> I apologize for a simple non-root question, but sorrowly I have
> nobody else to ask:
> Sometimes I have statements such as the following:
>    if (strcmp(name, "option") == 0) {
>       char *option;
>       option = strcpy(option, opt);
>    }
> Although it is correct, I get the following compiler warning:
> "warning: `char*option' might be used uninitialized in this function"

This is not a minor warning; it is an error. The code above
works by luck. If your application is big and run for enough
time, it will eventually crash (you resolve these errors using
valgrind or electric fence).

>From the man page of strcpy(3):

The  strcpy() function copies the string pointed to by src
(including the terminating `\0' character)  to  the  array
pointed  to by dest.  The strings may not overlap, and the
destination string dest must be large  enough  to  receive
the copy.

The destination string here is the 'option' pointer and you
have not allocated any space for it.  

> How can I prevent such compiler warnings?
> Would it be save to write:
>       char *option = "";
> (If this is not save, why?)

No, this maybe elliminate the warning, but it is still an
error. Use malloc() to allocate enough space (don't forget
to reserve one char for the null termination).

University of Athens			I bet the human brain 
Physics Department				is a kludge --Marvin Minsky 


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