Use PHP regular expressions to clear whitespace in strings_PHP Tutorial

We often deal with data coming from user input or reading from the database, and there may be extra whitespace or tabs, carriage returns, etc. in your strings. Storing these extra characters is a bit of a waste of space.

If you want to remove the whitespace at the beginning and end of the string, you can use the PHP internal function trim(). However, we often want to clear the white space completely. You need to clear the starting and ending blanks, turn multiple blanks into one blank, and use a rule to handle other blanks of the same type.

This can be done using PHP regular expressions

The following example can remove extra Whitespace

$str = " This line containstliberal rn use of whitespace.nn";

// First remove the leading/trailing whitespace
//Remove the starting and ending whitespace
$str = trim($str);

// Now remove any doubled-up whitespace
//Remove the white space that is crowded with others
$str = preg_replace('/s(?=s)/', '', $str);

// Finally, replace any non-space whitespace, with a space
//Finally, remove the non-space whitespace and replace it with a space
$str = preg_replace('/[nrt] /', ' ', $str);

// Echo out: 'This line contains liberal use of whitespace.'
echo "

{$str}

" ;
?>


The above example removes all the blanks step by step. First we use the trim() function to remove the starting and ending whitespace. Then, we use preg_replace() to remove duplicates. s represents any whitespace. (?=) means look forward. It means that it only matches characters that are followed by the same character as itself. So this regex means: "Any whitespace character followed by a whitespace character." We replace it with whitespace, which removes it and leaves only the whitespace character.

Finally, we use another regular expression [nrt] to find any remaining newlines (n), carriage returns (r), or tabs (t). We replace these with a space.