This article defines a function substr_count() which can be used for count the occurrences of a character or substring in a string. In general way, substr_count() takes two arguments, first argument is a string and second argument is a character or a string which is to be search inside first argument. The function returns an integer value which defines the number of occurrences of substring found in the string.

Syntax : substr_count(string, search_string, start_index, length)

string : The main string to check for occurrences of search_string.(Required)
search_string : A character or a substring to search in string.(Required)
start_index : Specify the index for start searching.(Optional)
length : Defines the search length start from start_index.(Optional)

Note :

• The two optional parameters are added from PHP version 5.1.0
• If the length (start_index + length) is greater than the string of string, The function generates a warning.
• The search_string is case-sensitive.

Example 1 :

<?php
 $str = "This is a testing string";
 echo substr_count($str, 'i');
 echo "<br>";
 echo substr_count($str, 'is');
 echo "<br>";
 echo substr_count($str, 'is', 3, 8);
?>

Output : 4
2
1

Example 2 : substr_count() does not count overlapped substrings.

<?php
 $str = "abcabcabb";
 echo substr_count($str, 'abca');
?>

Output : 1