This tutorial will help you to check if a string contains any substring in PHP programming language. For example, you want to run a specific line of code only if any input string contains another substring in it.
Example 1.
The following code will evaluate to true because the main string $str contains the substring ‘This‘ in it. This will print “true”.
1 2 3 4 5 6 7 | <?php $str = 'This is Main String'; if (strpos($str, 'This') !== false) { echo 'true'; } ?> |
Example 2.
The following code will evaluate to false because the main string $str doesn’t contains the substring ‘Hello‘ in it. This will nothing print.
1 2 3 4 5 6 7 8 | <?php $str = 'This is Main String'; $substr = "Hello"; if (strpos($str, $substr) !== false) { echo 'true'; } ?> |
Example 3. String Contains Substring on Start
The following code will check if a String conatins a substring at start. The following code will evaluate to true because the main string $str contains the substring ‘This‘ at start.
1 2 3 4 5 6 7 | <?php $str = 'This is Main String'; if (strpos($str, 'This') === 0 ) { echo 'true'; } ?> |
Example 3 should use === instead of ==.
If $str does NOT contain the substring ‘This‘, then strpos($str, ‘This’) will return false.
Therfore, strpos($str, ‘This’) == 0 evaluates to true
Thank you Kim, I have updated tutorial.