Message-Id: <m0z4TdT-000S4VC@inti.gov.ar>
Comments: Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization: INTI
To: lubaldo AT adinet DOT com DOT uy
Date: Thu, 6 Aug 1998 14:26:17 +0000
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Subject: Re: How do I free the allocated memory?
CC: djgpp AT delorie DOT com
In-reply-to: <3.0.1.32.19980806004203.007a2750@adinet.com.uy>
References: <m0z43Vz-000S4XC AT inti DOT gov DOT ar>
Precedence: bulk

lubaldo AT adinet DOT com DOT uy wrote:

> At 10:32 AM 05/08/1998 +0000, you wrote:
> >gah AT jet DOT es (Grzegorz Adam Hankiewicz) wrote:
> >
> >> I wanted to create a function which accepts a char string, manipulates
> >> it at returns a new one. I thought about this:
> >> 
> >[snipped] 
> >> Ok, so I learned that after mallocing some memory I always have to
> >> free it. But know, since I am returning the pointer, I cannot free the
> >> memory before returning the pointer, and I cannot free the memory
> >> after (the compiler will never reach that line).
> >> 
> >> So, how do I free that allocated mem?
> >
> >1) Don't allocate the memory before checking new_str.
> >2) Don't allocate a fixed ammount, calculate it.
> >3) Use it
> >    new_s=modify_string(old);
> >    if (new_s)
> >      {
> >       .... use it ....
> >       free(new_s);
> >      }         
> >
> >Use something like that:
> >
> >> char *modify_string ( char *old_str)
> >> {
> >> 	char *new_str;
> >> 
> >> 	if (new_str == NULL) return NULL;
> 	Are you sure this is ok SET? You are comparing against a pointer that has
> garbage... whats the point? It can fail...

Yes sorry it must be:
> >> 	if (old_str == NULL) return NULL;
To avoid a crash if old_str was NULL.
 
> >> 	new_str = malloc (strlen(old_str)+1+ len added by the formatting
> string);  // That's enough for me.
> >> 
> >> 	sprintf( new_str, "Blah,blah %s", old_str);
> >> 
> >> 	return new_str;
> >> }
> >

set 
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