Subj : Re: malloc()
To   : borland.public.cpp.borlandcpp
From : Jan Vernimmen
Date : Thu Jun 24 2004 12:45 pm

Hi Wayne,

txtBuf is initialized as follows:

txtBuf = (char*)malloc( (size_t)LEN_MALLOCMINIM );  // LEN_MALLOCMINIM = 12
txtBuf[0] = '\0';

Jan.


Wayne A. King wrote:
> To restate the issue:
> 
> Your conditional statement
> 
>>if ( strlen( szInput ) > strlen( txtBuf ))
> 
> presupposes that txtBuf actually *contains* a nul-terminated string.
> 
> My question was/is:
> 
> What is the buffer's state on the *first* iteration of this loop?
> How was it initialized? You *cannot* use strlen() to determine
> the size of the *buffer*. It can only determine the length of any
> string *in* the buffer. Memory allocated with malloc is uninitialized.
> Its contents will be random - whatever happens to be in those
> memory locations at the time. Therefore, you *cannot* use
> strlen on a buffer immediately after malloc without first setting
> at least one of the bytes within the buffer to nul (binary zero in
> this case).
>

.