strrpos()

Introduction

The strrpos() function finds the last occurrence of a substring inside a string and returns its zero-based position (the index of its first character). Think of it as the mirror image of strpos(), which finds the first occurrence: strpos() scans left-to-right, strrpos() reports the right-most match.

You reach for strrpos() whenever you care about the end of a string — getting a file extension after the last dot, splitting a path on its final slash, or trimming everything after the last separator.

This page covers the syntax, the easy-to-miss false/0 pitfall, how the $offset parameter (including negative values) narrows the search, and the case-insensitive sibling strripos().

Syntax

strrpos(string $haystack, string $needle, int $offset = 0): int|false

Return value: the integer position (counting from 0) of the last match, or false if $needle never appears in $haystack. The position is a byte offset, so for multibyte text (UTF-8 accents, emoji) use mb_strrpos() instead.

Example Usage

Here is an example usage of the strrpos() function in PHP:

Example of PHP strrpos()

"Hello World" contains two o characters — at index 4 and index 7. Because strrpos() reports the last one, the output is:

Found last occurrence of 'o' in 'Hello World' at position 7

Always compare with === / !== false

This is the bug that bites everyone. When the match is at the very start of the string, strrpos() returns 0, and PHP treats 0 as falsy. A loose check like if ($result) would then wrongly conclude "not found":

<?php

// "h" is at position 0, so strrpos returns 0
$pos = strrpos("hello", "h");

if ($pos == false) {        // WRONG: 0 == false is true
  echo "not found";         // this prints, even though "h" WAS found
} else {
  echo "found at $pos";
}

The fix is the strict !== false operator (used in the first example), which distinguishes the integer 0 from the boolean false.

Narrowing the search with $offset

A negative offset is the most useful form: it tells strrpos() to stop searching that many characters before the end, which is handy for ignoring a trailing portion of the string.

<?php

$path = "a/b/c/d";

// Last slash overall:
echo strrpos($path, "/");        // 5

// Last slash, ignoring the final 2 chars ("/d"):
echo "\n";
echo strrpos($path, "/", -3);    // 3

A positive offset begins the search that many characters from the start, skipping earlier matches.

Case-insensitive search: strripos()

strrpos() is case-sensitive — strrpos("FOO", "o") returns false. When case should not matter, use strripos(), which has the identical signature but matches regardless of case:

<?php

$str = "PHP is the Programming language: php";

echo strrpos($str, "php");   // 33  (only the lowercase one matches)
echo "\n";
echo strripos($str, "php");  // 33  (right-most match, ignoring case)

Related functions

• strpos() — position of the first occurrence.
• stripos() — first occurrence, case-insensitive.
• substr() — extract the part of the string after the position you found.
• str_replace() — replace occurrences without needing their position.

Conclusion

strrpos() returns the byte position of the last occurrence of a substring, or false when there is none — so always compare its result with !== false. Combine it with a negative $offset to ignore trailing text, switch to strripos() for case-insensitive matching, and use mb_strrpos() when the string contains multibyte characters.

Practice