This is more of a C than a C++ solution, but it'll work for C++ as well.
If you're just starting out, you're probably doing mostly C'ish stuff
anyway.  (OTOH, maybe not, I've never taken a class on C or C++).

An easy way is to use the strtol() library function.  If the conversion
stops on something other than a null char, it's not a valid numeric value.

It'll go something like this:

	char *endofbuf;
	value = strtol(buf, &endofbuf, 10);
	if(*endofbuf != '\0')
	{
		moan();
	}
	if(value < 0)
	{
		moan();
	}

rna

On Wed, 16 Aug 2000, Eric Samson wrote:

> Thanks everyone, I will give it a shot when I get home.  I just thought that 
> it was odd that it ran from the prompt one day and not the next.  The book I 
> am using was pretty vague on the compiler syntax.  I compiled it without the 
> .o extension as well, I was about to go out and purchase code warrior, so 
> hopefully you guys just saved me some $$$  : )
> 
> I am pretty new to C++, compiling, etc., I really want to learn this 
> stuff...  I am trying to figure out how to validate input from a user to 
> make it accept only positive numeric values.  I was using a while loop to 
> check it, but when the user enters an alpha character, I get stuck in the 
> loop of death, I am sure many of you have experienced this.  I asked my 
> instructor how to do this, but he said that he wasn't sure.  would an if 
> statement nested in a while loop solve my problem??
> 
> Sorry about these newbie questions, but it's my second week in the class.. : 
> )
> 
> 
> ----Original Message Follows----
> From: Robert Ambrose <rna@testpt.com>
> Reply-To: plug-discuss@lists.PLUG.phoenix.az.us
> To: plug-discuss@lists.PLUG.phoenix.az.us
> Subject: Re: question for any C++ progammers
> Date: Wed, 16 Aug 2000 07:39:50 -0700 (MST)
> 
> 
> First the .o extension is for compiled but not linked modules.  Your
> command line should be something like 'g++ Assn2.cpp -oexp1', or more
> commonly: 'g++ Assn2.cpp -oAssn2'.
> 
> You problem is probably the 'current directory' is not in your PATH.  Try
> executing your program with './exp1.o'.
> 
> rna
> 
> On Wed, 16 Aug 2000, Eric Samson wrote:
> 
>  > Ok, this is frustrating...
>  >
>  > yesterday when I compiled some stuff I wrote in C++, I was able to run 
> the
>  > executable by typing exp1.o at the command prompt...  Today, I tried it
>  > again and got the following output:
>  >
>  > []$ cd ~/C++assignments
>  > [C++assignments]$ g++ Assn2.cpp -oexp1.o
>  > [C++assignments]$ dir
>  > Assn2.cpp      Currency2-1.o	     Currencycalc2-2.cpp   Currencycalc3.cpp
>  > Assn2.cpp~     Currency2-2.o	     Currencycalc2-2.cpp~  exp1.o
>  > Currency1.cpp  Currencycalc2-1.cpp   Currencycalc2.cpp
>  > Currency1.o    Currencycalc2-1.cpp~  Currencycalc2.cpp~
>  > [C++assignments]$ exp1.o
>  > bash: exp1.o: command not found
>  > [C++assignments]$
>  >
>  > For some reason my compiled program won't run today, but it did yesterday
>  > using the exact same commands.  I love linux, but little inconsistent 
> crap
>  > like this is really aggrivating...  I re-installed the gcc RPM's and
>  > upgraded my BASH shell to no avail...  I need some help here, or it's 
> back
>  > to M$ Visual C++ to get my school work done.  I am trying to avoid this,
>  > especially since I got done telling my class how great open source and 
> Linux
>  > are, but now I might have to eat my words next week...  ANY help would be
>  > appreciated..
>  >
>  > Thanks in advance,
>  >
>  > Eric
>  >
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