Newbie C++ programmer again...

[Eric Samson]

Ok, I looked up some reference on the syntax you used, and I am not sure I 
understand it..  From what I gathered, (cin >> foo) is actually a test to 
see if the input is of the type declared and it returns a NULL if not and a 
non-NULL is legal?


----Original Message Follows----
From: Robert Ambrose <rna@testpt.com>
Reply-To: plug-devel@lists.PLUG.phoenix.az.us
To: plug-devel@lists.PLUG.phoenix.az.us
Subject: Re: Newbie C++ programmer again...
Date: Fri, 18 Aug 2000 09:33:02 -0700 (MST)


The short answer is the state in the ios parent class has to be reset to
good (cleared).  The long answer reauires to much typing ;-), and I've
spent to much time on this already (anthough I did learn some usefull
things).  If you really want to know, I'm always happy to talk it over a
beer.

Here's a working program:

#include <iostream.h>
#include <ctype.h>
#include <limits.h>

int main ()
{
	for(;;)
	{
		double dollars;	// Maybe I'll win the lotto

		cout << "Enter dollars:";

		if(cin >> dollars)
		{
			double pounds;

			pounds = dollars / 1.49;
			cout << "is " << pounds << " pounds" << endl;
			break;
		}
		else
		{
			cin.clear();
			cin.ignore(INT_MAX, '\n');
			cout << "Not a valid dollar ammount, try again" << endl;
		}
	}

	return 0;
}

rna

On Fri, 18 Aug 2000, Eric Samson wrote:

 > Ok, I have about gone nuts trying to figure this out...
 >
 > This is my assignment that I am having trouble with..
 >
 > It's a simple currency converter, the user enters a float which indicates
 > how many US dollars they want to convert to a specified currency, in my 
case
 > Deutchmarks...  That is the easy part, got it written no problem, simple
 > math... An optional part of the assignment is to validate the user input 
and
 > be sure it is a numeric value (float), and not an alpha charater, symbol,
 > etc...  If they enter something that will not work, they are supposed to 
be
 > prompted to try to enter the info again...  Preventing negative values is 
no
 > problem with the <while (someinput < 0)> loop, but if they enter an alpha
 > value, it enters an infinite loop.  I went to borders last night and my
 > roommate and I (mostly because he is tired of hearing me whine about it)
 > looked in a bunch of books for a solution, and didn't have any luck.  My
 > instructor was no help either, he wasn't sure how to do it (he is a VB
 > programmer teaching C++, go figure)...  This seems like something that
 > should be painfully simple...  Is this something too complex for a 
beginning
 > programmer?  I should think that it would be a basic part of programming,
 > but I could be wrong...  I notice a few people on here saying they don't 
use
 > C++ much, so what is the language of choice for programming in Linux?
 >
 > Thanks again,
 >
 > Eric
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