Accept only numeric value

[karthik2423]

Hi,
Please let me know how I can accomplish the following task -
"Ask the user to enter a number".
Check whether the user has entered only numeric values. If he/she enters any character other than 0-9, it should print out an error.

Thanks,
Karthik

[KevinADC]

What have you tried so far?

[miller]

The experts on this site are more than happy to help you with your problems but they cannot do your assignment/program for you. Attempt the assignment/program yourself first and post questions regarding any difficulties you have or about a particular function of the code that you don't know how to achieve.

Please read the Posting Guidelines and particularly the Coursework Posting Guidlines.

Then when you are ready post a new question in this thread.

MODERATOR

[Lastknight]

karthick
go to w3schools or tizag.com and int that sites go through the javascript tutorial if u need to validate the form field only with numbers or else try to copy a sample code ur doing now in to this forum.

So that people can help u clearly..

regards,
Lastknight

[karthik2423]

What have you tried so far?

Hi Kevin,
This is the program I have written so far..
#!/usr/bin/perl
use strict;
use warnings;
print "Enter a numeric value\n";
my $num = <STDIN>;
chomp($num);
if ( $num !~ /[0-9])
{
print "Enter a numeric value only\n";
}
else
print "Numeric value entered is $num\n";


But this program accepts values like '99a, a99' etc..

Cheers,
Karthik

[karthik2423]

The experts on this site are more than happy to help you with your problems but they cannot do your assignment/program for you. Attempt the assignment/program yourself first and post questions regarding any difficulties you have or about a particular function of the code that you don't know how to achieve.

Please read the Posting Guidelines and particularly the Coursework Posting Guidlines.

Then when you are ready post a new question in this thread.

MODERATOR

Thanks for the info Miller...I had written the program..but was too lazy to post it out here..sorry..I have posted it now.. ;)
Thanks,
Karthik

[KevinADC]

You need to use "anchors" in your regexp:

if ( $num !~ /^[0-9]$)

With all of the regexps above, if the regexp matched anywhere in the string, it was considered a match. Sometimes, however, we'd like to specify where in the string the regexp should try to match. To do this, we would use the anchor metacharacters ^ and $ . The anchor ^ means match at the beginning of the string and the anchor $ means match at the end of the string, or before a newline at the end of the string. Here is how they are used:

You can find the above in this regexp tutorial:

http://perldoc.perl.org/perlretut.html

somewhere in Part 1. The Basics

[RuslanDashinsky]

For matching 1 or more then one digit use " * "


if ($num !~ /^[0-9]+$/) {
do something
}

[Ganon11]

Couldn't you also match for any non-numeric character?

if ($num =~ /[^0-9]/) { # If $num matches for any character that isn't 0-9

[KevinADC]

For matching 1 or more then one digit use " * "


if ($num !~ /^[0-9]+$/) {
do something
}

I guess you meant "+", which is correct, not "*". Please note the date of threads. You have posted in a very old one.

[KevinADC]

Couldn't you also match for any non-numeric character?

if ($num =~ /[^0-9]/) { # If $num matches for any character that isn't 0-9

You could but that is sort of twisted logic. It is also more clearly written like this:

if ($num =~ /\D/) {
    print "Found a non-digit";
}
 

\D is the compliment of \d