(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
mb_substr_count — Count the number of substring occurrences
$haystack, string $needle, ?string $encoding = null): int
   Counts the number of times the
   needle substring occurs in the
   haystack string.
  
haystackThe string being checked.
needleThe string being found.
encodingThe encoding
parameter is the character encoding. If it is omitted or null, the internal character
encoding value will be used.
   The number of times the
   needle substring occurs in the
   haystack string.
  
| Version | Description | 
|---|---|
| 8.0.0 | encodingis nullable now. | 
Example #1 mb_substr_count() example
<?php
echo mb_substr_count("This is a test", "is"); // prints out 2
?>