PHP – mb_strcut() function

The mb_strcut() function in PHP is used to extract a substring from a string based on byte positions rather than character positions. This is particularly useful when working with multi-byte character encodings like UTF-8, where a single character might use multiple bytes.

Syntax

string mb_strcut(
   string $str,
   int $start,
   int $length = null,
   string $encoding = null
);

Parameters

The mb_strcut() function accepts the following parameters −

• str − The input string to be cut.

• start − The starting byte position. If positive, counting starts from the beginning (0-indexed). If negative, counting starts from the end of the string.

• length − The maximum number of bytes to extract. If omitted or null, extracts from start position to the end of the string.

• encoding − The character encoding. If omitted, uses the internal character encoding.

Return Value

Returns the extracted portion of the string as a string, or an empty string if the start position is beyond the string length.

Basic Example

Here's a simple example demonstrating how to extract a substring −

<?php
   $string = "Hello World";
   $result = mb_strcut($string, 6, 5, "UTF-8");
   echo $result;
?>

World

Working with Multi-byte Characters

The function handles multi-byte characters properly, ensuring cuts don't break character sequences −

<?php
   $string = "???????"; // Japanese text
   $result = mb_strcut($string, 0, 9, "UTF-8");
   echo $result;
   echo "<br>";
   echo "Bytes extracted: " . strlen($result);
?>

???
Bytes extracted: 9

Negative Start Position

Using negative start positions to extract from the end of the string −

<?php
   $string = "TutorialsPoint";
   $result = mb_strcut($string, -5, 5, "UTF-8");
   echo $result;
?>

Point

Conclusion

The mb_strcut() function is essential for byte-level string manipulation in multi-byte character environments. It ensures proper handling of character boundaries, making it safer than simple byte-cutting operations when working with UTF-8 and other multi-byte encodings.