How to Check If String Contains Substring in PHP

How do I check a string contains any specific word or substring in PHP. This tutorial will help you to check if a string contains a substring in the PHP programming language. For example, you have to execute a line of code only if an input string contains a specific substring. If substring found then execute further code otherwise else part will execute.

Check If String Contains a Specific Word in PHP

You can use the PHP strpos() function to check whether a string contains a specific substring or not.

The strpos() function returns the position of the first appearance of a substring in a string. If the substring is not found then it returns false.

Syntax

int strpos( $String, $Substring )

Parameter – The strpos() function accepts two parameters.

• $String – This parameter specifies the text where searching performs.
• $Substring – This parameter specifies the substring which we have to search.

Note: The strpos() function check string positions start from 0, and not the 1.

Example 1

The following example code snippet checks whether a specific word exists in the given string or not. It returns true because $str contains the substring “first” in it. Finally, this will print “The word ‘first’ was found”.

<?php
$str = 'This is the first paragraph of an essay.';
$word  = "first";

if (strpos($str, $word) !== false) {
    echo "The word '$word' was found";
} else {
    echo "The word '$word' was not found";
}
?>

Note – The strpos() function is used for case-sensitive comparison. However, you can use the stripos() function for case-insensitive comparison in PHP.

Example 2

The following example code snippet checks case-insensitively whether a substring exists in the given string or not. It returns true because $str contains the substring “Essay” in it. Finally, this will print The word ‘Essay’ was found.

<?php
$str = 'This is the first paragraph of an essay.';
$word  = "Essay";

if (stripos($str, $word) !== false) {
    echo "The word '$word' was found";
} else {
    echo "The word '$word' was not found";
}
?>

Example 3

In the following example, you will see the substring exists at the beginning position in the given string or not. However, it returns true because $str contains the substring “This” at the start position. Thus, this will print The word ‘This’ was found at the beginning.

<?php
$str = 'This is the first paragraph of an essay.';
$word  = "This";

if (strpos($str, $word) === 0) {
    echo "The word '$word' was found at the beginning";
} else {
    echo "The word '$word' was not found at the beginning";
}
?>

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