Padding out a string

string str_pad ( string input, int pad_length [, string pad_string [, int pad_type]])

Next up, str_pad() makes a given string (parameter one) larger by X number of characters (parameter two) by adding on spaces. For example:

    $string = "Goodbye, Perl!";
    $newstring = str_pad($string, 10);

That code would leave " Goodbye, Perl! " in $newstring, which is the same string from $string except with five spaces on either side, equalling the 10 we passed in as parameter two.

Str_pad() has an optional third parameter that lets you set the padding character to use, so:

    $string = "Goodbye, Perl!";>
    $newstring = str_pad($string, 10, 'a');

That would put "aaaaaGoodbye, Perl!aaaaa" into $newstring.

We can extend the function even more by using it is optional fourth parameter, which allows us to specify which side we want the padding added to. The fourth parameter is specified as a constant, and you either use STR_PAD_LEFT, STR_PAD_RIGHT, or STR_PAD_BOTH:

    $string = "Goodbye, Perl!";
    $a = str_pad($string, 10, '-', STR_PAD_LEFT);
    $b = str_pad($string, 10, '-', STR_PAD_RIGHT);
    $c = str_pad($string, 10, '-', STR_PAD_BOTH);

That code will set $a to be "----------Goodbye, Perl!", $b to be "Goodbye, Perl!----------", and $c to be "-----Goodbye, Perl!-----", as expected.

Note that HTML only allows a maximum of one space at any time. If you want to pad more, you will need to use "&nbsp;", the HTML code for non-breaking space.


Want to learn PHP 7?

Hacking with PHP has been fully updated for PHP 7, and is now available as a downloadable PDF. Get over 1200 pages of hands-on PHP learning today!

If this was helpful, please take a moment to tell others about Hacking with PHP by tweeting about it!

Next chapter: Complex string printing >>

Previous chapter: Comparing strings

Jump to:


Home: Table of Contents

Copyright ©2015 Paul Hudson. Follow me: @twostraws.