[ILUG] C string concat question ??

[Dave Neary]

On Wed, May 02, 2001 at 05:58:59PM +0100, Glen Gray wrote:
> Looking for a simple way to cat two strings into a third.
> 
> I had the following in my code
> 
> msg = strdup(strcat(strvar1, strvar2));
> 
> What happens here is the strvar2 is concatinated to strvar1 and a
> pointer to strvar1 is returned to strdup which allocates memeory for the
> char *message variable.
> 
> Glen

After reading Kenn's solution, I have to say I agree with him :)
Stretch it out! But if you wanted the short way, you could always
(after properly allocating space for msg) do
    msg=strdup(strvar1), 
    (msg = realloc(msg, strlen(strvar1) + strlen(strvar2) +
    1))==NULL? realloc_failed_stuff(__FILE__, __LINE__): 1, 
    strcat(msg, strvar2);

Of course, there's nothing stopping you from putting the whole
program on one line using the comma operator. As long as you
don't use if, while or for statements :)

And my first instinct...
strcat(msg=strdup(strvar1),strvar2); 
doesn't work because you can never be sure what order the
arguments will evaluate. So strcat might cat strvar2 on the
(uninitialised) msg before strdup over-writes it with strvar1.

Cheers,
Dave.

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