Php check if string is contained in string

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Checking if a String Contains a Substring in PHP

To check if a PHP string contains a substring, you can use the strpos($string, $substring) function. If the string contains the searched substring, the strpos() function will return the index of the first occurrence of the substring in the string; otherwise «false». In PHP, indexes start at 0. As of PHP 8+, you can use the new str_contains($string, $substring) function to check if a string contains the desired substring or word. The str_contains() function returns «true» if the string contains a substring or «false» otherwise. Also, you can use Regular Expressions to check if a PHP string contains a substring. Regular Expressions, unlike other methods, provide more flexibility but are slower. In this PHP String Contains Substring example, we use the strpos() function to check if the string contains a substring. Click Execute to run the PHP String Contains example online and see the result.

What is a string in PHP?

PHP strings are sequences of characters, where each character is represented by one byte. Hence PHP supports 256 different characters, and there is no native support for Unicode. String variables in PHP can contain alphanumeric characters. PHP provides a wide set of built-in functions for splitting, comparing, concatenating, replacing, and interpolating strings. You can also convert string to array, convert string to int, and find the length of a string.

$str = 'An example of a PHP string in single quotes.'

$str = "An example of a PHP string in double quotes.\r\n"

Checking if a string contains a substring using PHP built-in functions

You can use the strpos() and stripos() functions to check if a PHP string contains a substring. The strpos() method searches for an occurrence of a substring in a PHP string and returns the index of the first occurrence or «false» otherwise. The strpos() method is case-sensitive. If you want to check if a PHP string contains a substring case-insensitive, you can use the stripos() method or convert the string and substring to lowercase before checking. The following is the syntax of the PHP strpos() and stripos() functions:

strpos(string, substring, start) stripos(string, substring, start)

string (required): the string to search in;
substring (required): the string to search for;
start (optional): position from which to search. If the start is a negative number, the search is performed from the end of the string.

Читайте также: Append метод в питоне

In PHP 8 and higher, you can use str_contains() function to check if a string contains the desired substring. The str_contains() function returns the boolean «true» if the substring is found in the string and «false» otherwise. The str_contains() is case-sensitive. The following is the syntax of the PHP str_contains() function:

str_contains(string, substring)

string (required): the original string;
substring (required): the substring to search for in the string.

PHP String Contains a Substring Examples

The following are examples of checking if a string contains a substring in PHP:

Checking if the PHP string contains a substring using str_contains()

The following is an example of checking if a PHP string contains a substring using the new PHP 8 str_contains() function:

Checking if the PHP string contains a substring using strpos (case-sensitive)

The following is an example of checking if a substring exists in a PHP string in a case-sensitive way using the strpos() function:

Checking if the PHP string contains a substring using stripos (case-insensitive)

The following is an example of checking for the presence of a substring in a PHP string case-insensitively using the stripos() function:

Checking a PHP String for a Substring with Regular Expressions

The following are examples of checking if a string contains a substring using Regular Expressions in PHP:

Checking if the PHP string contains a substring using preg_match()

To test a string for a substring using regular expressions, you can use the preg_match() function. The following is an example of checking if a substring exists in a PHP string using the preg_match() function:

Using Regular Expressions to check if a string contains a substring, case-insensitively:

To check for a substring in a string case-insensitively using regular expressions, you need to add anchor «i» to the Regular Expression:

/i", $str)) < echo 'Found'; >else < echo "Not Found!"; >?> #output: Not Found!

Using the Regex function to search specific words in a string

To find a specific word in a string using a Regular Expression, you need to add anchor «\b» to the Regular Expression:

\b/i", $str)) < echo 'true'; >else < echo 'false'; >?> #output: false

How to Check if a String Contains Another Substring in PHP

Monty Shokeen Last updated Feb 26, 2021

A lot of times when I am working with strings in PHP, it becomes important to check if a string contains another substring. PHP has a lot of functions to help you manipulate strings any way you like. We will be using some of these functions today to learn how to check if a string contains a specific substring.

Using New Functions in PHP 8

Three new functions have been added in PHP 8 to help us figure out if a string contains another substring. Please keep in mind that all these functions are case sensitive, and checking for the existence of an empty substring with them will always return true .

str_contains() checks if a string contains a specific substring.
str_ends_with() checks if a string ends with a specific substring.
str_starts_with() checks if a string starts with a specific substring.

$sentence = "Dolphins and Elephants are intelligent animals.";

if(str_contains($sentence, "Elephants"))

echo 'Elephants are intelligent.';

// Elephants are intelligent.

if(str_starts_with($sentence, "Dolphins"))

echo 'Dolphins are intelligent.';

echo 'There is a full stop at the end of the sentence.';

// There is a full stop at the end of the sentence.

As I mentioned earlier, these functions perform a case-sensitive match. You can also perform a case-insensitive match with them by first converting both the string and substring to the same case using strtolower() or strtoupper() .

These functions are ideal if you don’t want to get any extra information about the substrings, like their position. People who need extra information about the match should consider using the functions below.

Using strpos() and stripos()

You can use the PHP strpos() function to get the position of the first occurrence of a substring in a string. The function will return false if it cannot find the substring.

When you use strpos() to check for a substring, make sure that you use the strict inequality operator. This is because the position returned by strpos() starts with 0, and 0 can also equate to false . Using a regular equality check will give you false negatives if the substring is right at the beginning of the main string.

Here are some examples of strpos() :

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Php check if string is contained in string