PHP to check substring in a string

In PHP, you can check if a substring exists within a string using the strpos() function. This function returns the position of the first occurrence of a substring, or false if not found.

Using strpos() Function

The strpos() function is case-sensitive and returns the numeric position of the substring or false if not found ?

<?php
    $subStr = "Mother";
    $str = "How I Met Your Mother";
    echo "String = $str";
    echo "\nSubstring = $subStr";
    if(strpos($str, $subStr) !== false){
        echo "\nSubstring found successfully";
    } else{
        echo "\nSubstring not found";
    }
?>

String = How I Met Your Mother
Substring = Mother
Substring found successfully

Example with Substring Not Found

Here's an example where the substring is not present in the string ?

<?php
    $subStr = "Ocean";
    $str = "In the Heart of Sea";
    echo "String = $str";
    echo "\nSubstring = $subStr";
    if(strpos($str, $subStr) !== false){
        echo "\nSubstring found successfully";
    } else{
        echo "\nSubstring not found";
    }
?>

String = In the Heart of Sea
Substring = Ocean
Substring not found

Important Note

Always use the strict comparison operator !== when checking strpos() results, because if the substring is found at position 0, it returns 0 which evaluates to false in loose comparison.

Conclusion

The strpos() function is the most efficient way to check if a substring exists in a string. Remember to use strict comparison (!==) to avoid false negatives when the substring appears at the beginning of the string.