Re: [TCLUG:12705] A Little C Question

["John J. Trammell" <trammell@nitz.hep.umn.edu>]

Chris McKinley <lamfada@lugh.net> opined:
>
> On Fri, 21 Jan 2000, Jonathan Kline wrote:
>
> > I have the line #define base ='206.191.221.' above the function main in a
> > c file.  later on I create a loop and assign the remainder of the IP
> > address, So it selects a number, Anyone know how to combine base with the
> > final number?  This final IP has to be passed to a function
> > Any ideas?  Thanks.
> > 
>
> First off, don't use #define for this.  Use something like this in a
> header file if you need it hard coded.
>
> static char base[] = "206.191.221.";
>
> You need a function to turn an int to a string (null terminated array),
> call it char * int_to_str(int);

sprintf() would work just delovely for this.

> It would be better if it were a command line option.  Then do something
> like this:
>
> char * addr = malloc(16); /* xxx.xxx.xxx.xxx\0 */
> strcpy(addr,base);
> strcpy(&addr[12],int_to_str(host));

sprintf(addr,"%s%03d",base,host);

> it would actually be better to figure out how big base and host are, and
> use strncpy, returning errors where appropriate to avoid buffer
> overflows.  See the man pages for malloc, strcpy, strlen, etc.

Eh.  You sure you can't do it in Perl?  :-)