How to check if string contains substring in PHP

    RahulBy 2 Mins ReadUpdated:

    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”.

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    <?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.

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    <?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.

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    <?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.

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    5 Comments

    1. Mern on

      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?

      Reply
    4. Kim Kline on

      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

      Reply

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