note 96029 deleted from function.preg-replace by danbrown

Note Submitter: anonymous ---- The PHP function preg_replace() has powerful functionality in its own right, but extra depth can be added with the inclusion of the <B>e</B> modifier after the pattern. Take the following bit of code, which just picks out the letters of a string and replaces them with the letter X. <?php $something = 'df1gdf2gdf3sgdfg'; $something = preg_replace("/([a-z]*)/", "X", $something); echo $something; // XX1XX2XX3XX ?> This is simple enough, but using the <b>e</b> modifier after the pattern allows us to use <B>PHP functions</B> within the replace parameters. The following bit of code turns all letters upper case in a string of random letters by using the strtoupper() PHP function. <?php $something = 'df1gdf2gdf3sgdfg'; $something = preg_replace("/([a-z]*)/e", "strtoupper('\\1')", $something); echo $something; // DF1GDF2GDF3SGDFG ?> Here is another example, but in this case the full string is repeated after the modified string. <?php $something = 'df1gdf2gdf3sgdfg'; $something = preg_replace("/([a-z0-9]*)/e", "strtoupper('\\1').'\\1'", $something); echo $something; // DF1GDF2GDF3SGDFGdf1gdf2gdf3sgdfg ?> Notice that when using the <b>e</b> modifier it is important to properly escape the string with single and double quotes. This is because the string as a whole is parsed as PHP and so if you don’t put single quotes around the backreferences then you will get PHP complaining about constants.