How to Clean Up the Start & End of a String in Perl

Perl does not have a built-in function that removes whitespace from the beginning or end of a string, but you can use the built-in substitution operator to perform the same function. The substitution operator uses standard regular expressions to replace a portion of a string with other characters. Removing whitespace can help clean up and validate user input, and you can also use it to remove unnecessary space in a text file.

Instructions

1. Open a blank plain text document.

2. Type the following lines to start the Perl script:

   #!bin/perl
   use strict;
   use warnings;

3. Type the following lines to create a string that contains whitespace at the beginning and the end of the string, and print the string to the screen:

   my $orig_string = " This is a string ... ";
   print $orig_string."\n";

4. Type the following lines to remove the whitespace from the beginning of the string and print the edited string to the screen:

   $orig_string =~ s/^\s+//;
   print $orig_string;

5. Type the following lines to remove the whitespace from the end of the string and print the edited string to the screen:

   $orig_string =~ s/\s+$//;
   print $orig_string."\n";

6. Save and close the file.

Tips & Warnings

• Use the substitution operator to remove any specified characters from the beginning or end of a string.

References

• Perldoc.perl.org: S
• Somacon.com: Perl Trim Function to Strip Whitespace From a String

Resources

• The Perl Programming Language: Homepage