programming-examples/perl/Regular_Expression/digit.pl

#Determine if a string has a digit.!

use strict;
use warnings;

$string = "hello there";

if ( $string =~ /[0-9]/ ) {
   print "'$string' has a digit.\n";
}
else {
   print "'$string' has no digit.\n";
}

$string = "this one has a 2";


if ( $string =~ /[0-9]/ ) {
   print "'$string' has a digit.\n";
}
else {
   print "'$string' has no digit.\n";
}

   
    
#Check for no digit!

#!/usr/bin/perl -w

foreach $patt (@ARGV) {

    # Check for no digit.
    if ($patt =~ /\D/) {
        print "\tFound non-digit in \"$patt\".\n";
    }
}

   
    
 #Check for digit!

#!/usr/bin/perl -w

foreach $patt (@ARGV) {
    # Check for digit.
    if ($patt =~ /\d/) {
        print "\tFound a digit in \"$patt\".\n";
    }

}

   
    
 #if ($text =~ /(\d+)/) {print "Here's the number of apples: $1.\n";}!

$text = "I have 4 apples.";
if ($text =~ /(\d+)/) {print "Here's the number of apples: $1.\n";}

   
    
    
#if ($text =~ /\D/) {print "It's not a number.";}!

$text = "Hello!";

if ($text =~ /\D/) {print "It's not a number.";}

   
    
    
 #if ($text =~ /^[+-]\d+\.\d*$/) {print "It's a number.";}!

$text = "-3.1415";
if ($text =~ /^[+-]\d+\.\d*$/) {print "It's a number.";}

   
    
#if ($text =~ /^\d+$/) {print "It's a number.";}!

$text = "345";
if ($text =~ /^\d+$/) {print "It's a number.";}

   
    
    
 #A simple integer-validation program.!
  
#!/usr/local/bin/perl 

print ("Enter a number:\n"); 
$number = <STDIN>; 
chop ($number); 
if ($number =~ /^-?\d+$|^-?0[xX][\da-fa-F]+$/) { 
    print ("$number is a legal integer.\n"); 
} else { 
    print ("$number is not a legal integer.\n"); 
} 

   
    
    
 # Get all numbers!

#!/usr/bin/perl

use warnings;

my $text = "3 A, 2 B, and 0 C";

$text =~ s/\b(\d+)\b/$1 > 0?$1 > 1?$1 > 2? "Several":"A pair of":"One":"No"/ge;

print $text, "\n";

   
    
    
 #Match the one or more alphanumerics.!

$p = "This is a pattern test.";

if ($p =~ /(\w)*/){ print "$1\n"; }

if ($p =~ /(\w)+/){ print "$1\n"; }

   
    
    
 #Match numbers!

#!/usr/bin/perl
use warnings;
use strict;

my $text = "One Two Three 456 Seven";
while ($text =~ /[0-9]+/g) {
    print " \$& = $& \n \$` = $` \n \$' = $' \n";
}

   
    
    
  #Matching Any Letter or Number!

range [a-z] matches any lowercase letter
range [A-Z] matches any uppercase letter
/[A-Z][A-Z]/ matches any two uppercase letters. 
To match any uppercase letter, lowercase letter, or digit, use the following range: /[0-9a-zA-Z]/ 

   
    
    
   #Match one or zero alphanumerics followed by a single space character!

$p = "This is a pattern test.";

if ($p =~ /(\w?\s)/){ print "$1\n"; }
if ($p =~ /(\w\s)/){ print "$1\n"; }