A String is a sequence of characters, which is used either as a literal constant or as some kind of variable. A specific part of a string is known as substring.
The PHP provides strpos() function to check if a string contains a specific substring or not. The strpos() function returns the position of the first occurrence of a substring in a string. If substring not found, it return false as output.
This tutorial provides you three examples to check if a string contains a substring or not. Also you can check if the substring is at start of main string.
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'; } ?> |
Output: 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'; } ?> |
Output: none
Example 3.
The following code will check if a String contains 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'; } ?> |
Output: true
Conclusion
In this tutorial, you have learned to check if a string contains a substring using PHP programming language.
5 Comments
Hi, i have a rather twisted task similar to this post. If i want to check for sub strings in a string and want to put spaces and whole words to account, how do i do that? For example; the string “This is main string”, if i use it to check for the sub string “Th” it should not be true unless i put the whole word “This”, and if i want to get the phrase “is main” it should return true. How can i achieve that in php?
Just a test comment, but a nice article.
thanks for nice article
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.