How To Strip All Non-Alphabetic Characters From A String?

String manipulation is the common thing to do with web application development. It is very easy to get it done when you are having a complete library to deal with it. PHP has a very vast support on string manipulation and has many functions including regular expressions support.

Sometimes you may need to work with user inputs to get only the alphabets. I searched a lot on google but didn’t find a suitable example to get it done. So I spent time, re-searched on net and created an example for myself and to share with you all. Hope it saves time for you in your development.

Here is the code beauty: I created a function, so that you can simply re-use it without any further modifications.

<?php
 
    //the text before, we usually get it from user input
    $string = 'Remove all non-alphabetic characters: äósa Sachin9Kumar %^$2423Raj#*8put';
 
    //prints the text before
    echo 'Before: ' . $string . '<br />';
 
    //prints the result string with having only alphabets
    echo 'After: ' . allowAlphabets($string);
    //It will return: Remove all non alphabetic characters sa Sachin Kumar Raj put
 
    //@description:     replace all non-alphabets characters from the given string.
    //@return     :     result string or false
    function allowAlphabets($string){
 
        //create an array which has only allowed characters set
        $allow_characters=array('a','b','c','d','e','f','g','h','i','j','k',
        'l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B',
        'C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S',
        'T','U','V','W','X','Y','Z');
 
        //start of regx pattern
        $pattern = "@[^(";
 
        //generate a regx pattern 
        foreach ($allow_characters as $char) {
            $pattern .= preg_quote($char, "@");
        }
 
        //close the regx pattern string
        $pattern .= ")]@";
 
        //replace all non alphabets characters with space
        $after = preg_replace($pattern, " ", $string);
 
        //prints the result string with having only alphabets
        return $after;
    }
?>