perldoc -q number

• perlintro
• Scalar::Util::looks_like_number
• perlre [0-9]

perldoc -f number

No documentation for perl function `number' found

perldoc number

I made a typo:

perldoc -q number
[download]

The basic structure is some sort of a loop that stops when some "quit" or "exit" condition is satisfied. I like to use "while" loops.

Standard reaction when a blank line is input is to just re-prompt - that is not an error.

Standard reaction when blanks occur either before or after the input, is nothing! These extra leading or trailing blanks are not errors.

#!/usr/bin/perl -w
use strict;

while ( (print "Enter a number: "), 
        (my $number = <STDIN>) !~ /^\s*q(uit)?\s*$/i  
      )
{
     next if $number =~ /^\s*$/;  # re-prompt on blank line
     
     if ($number =~ /^\s*[-+]?[0-9]*\.?[0-9]+\s*$/) #a decimal floatin
+g point
     {
        print "Great! number is: $number\n";
     }
     else
     {
        print "illegal number - try again!\n";
     }
}
[download]

Above, you have several good answers to turn in (this is homework, isn't it? If so, better to label it so there's no question about your integrity) but your original code suggests you'll benefit from some of the pointers in the comments below:

#!/usr/bin/perl
use strict;        # strict and warnings are your friends. USE THEM AL
+WAYS!
use warnings;
# 923876

my $num;
input();           # you need not dump all your functions into subs
                   # and certainly not into chained subs, but using ch
+ained subs
                   # here makes it easier for me to point out a few th
+ings

=head 

print "\n Press any key to exit"; # Utterly unnecessary - 
                                  # your program will exit when it run
+s out of 
$key = <STDIN>;                   # instructions, absent code to speci
+fically do 
                                  # otherwise ... such as sub quit_or_
+repeat:
#End of Program

=cut


sub input
{
    print "Enter an integer that is between 0 and 9: ";  # no newline 
+so user can
    chomp ($num = <STDIN>);                              # enter data 
+at prompt
     test_input();
}

sub test_input 
{
    if ( $num =~ /^[1-8]$/ ) {   # 1...8 are the numbers "between 0 an
+d 9" 
                                 # as spec'ed by the prompt in OP's co
+de
        main();
    } else {
        print "Only single-digit, positive integers, 1 - 8, are allowe
+d\n";
        input();
    }
}

sub main 
{
    for(my $i=1; $i<=$num; $i++) {
        print "$i "; 
    }
    print "\n";
    quit_or_repeat();    # sub called here actually does something
                         # contrast w/ the original "$key = <STDIN>
                         #                           # End of Program"
+ 
}

sub quit_or_repeat 
{
    my $key = '';
    print "\n Press 'q' to quit or any other key to continue: ";
    chomp ($key = <STDIN>);
    if ( lc($key) eq 'q' ) {   # either 'q' or "Q" quits
        exit;
    } else {
        input();               # go another round
    }
}
[download]

Can you show us what you have so far?

If you don't have anything yet, you might consider building a loop that reads from STDIN, and then checks the string for non-numeric characters with a regular expression. Don't forget to chomp! Once the string is in the format you want, leave the loop and process it however you want.

This is what I have tried

print "Enter a number\n";
$num = <STDIN>; 
if ($num < 0)
{
   print "please enter a number that is between 0 and 9 \n";
   $num = <STDIN>;
}
 
                                                           #Get input 
+from the keyboard
for($i=1;$i<=$num;$i++)                          #For loop to repeat a
+ set of statements until a condition is met
{
    print $i;             

}

print "Press any key to exit";
$key = <STDIN>;
#End of Program
[download]

If you really meant 0..9, then use

if ($number =~ /^[0-9]$/) { ...
[download]

my $num;
{
    print "Please type a number: ";
    chomp($num = <>);
    redo unless $num =~ /^[0-9]+$/;
}
[download]

...
print "enter a number"
my $num = <STDIN>
unless ($num =~/[0-9]+/){
print "this is not a number\n please type a number"
}
print "your number is $num";
...
[download]

mmh, I forgot all ";" and this don't go

much better like this:

...
print "enter a number: \n";
my $num = <STDIN>;
if ($num !~/^[+-]?\d+$/){
print "this is not a number\n please type a number\n";
}
else {print "your number is $num\n"}
...
[download]

Update: my $num = int(<STDIN>); thus, 12.45 now is a number

ups... not so good idea,

enter a number: dfr34

your number is 0

hohohou...

use strict;
print "enter a number: ";
my $num = <STDIN>;
if ($num !~/^[+-]?\d+\.?\d*$/){print "this is not a number\n"}
else {print "your number is $num\n"}


__OUTPUT__
34  -> your number is 34
34.56  -> your number is 34.56
-1 -> your number is -1
34gtf -> this is not a number
[download]

Thanks..This is what I was looking for..