How to remove non-alphanumeric characters from string in PHP

#Non-alphanumeric characters can be removed using the preg_replace() function. This function performs a regular expression search and replace. The function preg_replace() searches for the string specified by pattern and replaces the pattern with replace if found.

Code example:

Method 1: Regular expression '/[\W]/' matches all non-alphanumeric characters , and replace them with '' (empty string).

$str = preg_replace( '/[\W]/', '', $str);

In regular expressions, W is a metacharacter preceded by a backslash (\W), which is used to give the combination special meaning. It represents a combination of non-alphanumeric characters.

Example:

Output:

phpcn2019

Method 2: Regular expression '/ [^ a-z0-9] / i' matches all non-alphanumeric characters and replaces them with '' (the empty string).

$str = preg_replace( '/[^a-z0-9 ]/i', '', $str);

In regular expressions:

i: It is used for case insensitivity.

az: It is used for all lowercase letters, since i is already mentioned in the statement (case insensitive), there is no need to specify AZ.

0-9: used to match all numbers.

<?php 
//包含非字母数字字符的字符串
$str="!@php.cn2019?";
// preg_replace函数删除
//非字母数字字符
$str = preg_replace( &#39;/[^a-z0-9]/i&#39;, &#39;&#39;, $str);
//打印字符串
echo($str);
?>

Output:

phpcn2019

preg_replace Syntax:

int preg_match( $pattern, $replacement_string, $original_string )

Parameters: The function accepts three parameters as mentioned above, as described below:

$pattern: The pattern searched in the string. It must be a regular expression.

$replacement_string: The matched pattern is replaced by replacement_string.

$original_string: This is the original string to complete the search and replace.

Return value:

After the replacement occurs, the modified string will be returned.

If no match is found, the original string remains unchanged.

This article is about how to delete non-alphanumeric characters in PHP. It is also very simple and easy to understand. I hope it will be helpful to friends in need!

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