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PHP program to remove special characters from a string

Here, we are going to implement a PHP program to remove special characters from a string.
Submitted by Sayesha Singh, on August 10, 2020 [Last updated : March 13, 2023]

PHP - Removing Special Characters from a String

Characters other than alphabets and numbers are called special characters. And they can have used more than one which is doesn't happen in the case of alphabets or numbers.

There following ways (functions) can be used to remove special characters from the given string,

1. Using preg_replace()
2. Using str_replace()

1) Using preg_replace()

This is the most used method. A pattern can be inputted which will be replaced everywhere in the string.

preg_replace() function can be used in PHP for searching and replacing. It always returns either a string or an array, according to what was searched and replaced.

Syntax

    preg_replace(
        $word_to_replace, 
        $new_word, 
        $string_to_be_searched, 
        $limit, 
        $count
        )

In the given example we have a sentence from which every special character including space is removed,

PHP code to remove special characters from a string using preg_replace()

<?php
    #string
    $str = 'We welcome all of you to our school (of PHP).
    This--> school is one of its kind :).
    Many schools dont offer this subject :(';
    
    $str = preg_replace('/[^A-Za-z0-9]/', '', $str);
    
    // Printing the result
    echo $str;
?>

Output

WewelcomeallofyoutoourschoolofPHPThisschoolisoneofitskindManyschoolsdontofferthissubject

2) Using str_replace()

This is not common but it has its own importance. This differs from the first method in the sense that here programmer defines the special characters. He also decides what should the special characters be replaced with if the program encounters it.

str_replace() function is used for searching a regular expression and replacing a specific content in place of all the occurrences of searched expression. It always returns either a string or an array, according to what was searched and replaced. It has three mandatory parameters while one is optional. The compulsory parameters of the function are - value to be searched, the value it will be replaced with and the string in which this value needs to be searched. The optional parameter specifies the count of the number of times the replacement is needed.

Syntax

    str_replace(
        $word_to_replace, 
        $new_word, 
        $string_in_which_word_is_present
        )

PHP code to remove special characters from a string using str_replace()

<?php
    #string 
    $str= 'We, welcome all of you, to our school <of PHP>.
    This--> school is one of its kind :).
    Many schools dont offer this subject :(';

    $str = str_replace( array( '\'', '(',')', ',' , ':', '<', '>','.',' ','-' ), '',$str); 

    // Printing the result 
    echo $str;  
?>

Output

WewelcomeallofyoutoourschoolofPHP
Thisschoolisoneofitskind
Manyschoolsdontofferthissubject

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