Understanding and Using the PHP rtrim() Function

The rtrim() function is a built‑in PHP string function that removes whitespace (or other specified characters) from the end of a string.

What is rtrim()?

It trims trailing whitespace characters such as spaces, tabs, and newlines. The basic syntax is:

string rtrim ( string $str [, string $character_mask ] )

$str

is the input string, and $character_mask is optional; if omitted, all trailing whitespace is removed.

Usage Examples

1. Remove trailing whitespace

$str = "Hello World    ";
$result = rtrim($str);
echo $result; // Outputs: Hello World

This example defines a string with trailing spaces and uses rtrim() to produce a clean result.

2. Remove a specific character

$str = "Hello World!";
$result = rtrim($str, "!");
echo $result; // Outputs: Hello World

By providing "!" as the character mask, only the exclamation mark at the end is removed.

3. Remove multiple specified characters

$str = "Hello World!";
$result = rtrim($str, "!.");
echo $result; // Outputs: Hello World

Here the mask "!." tells rtrim() to strip both exclamation marks and periods from the string’s end.

Important Notes

The function only affects the end of the string; leading or interior whitespace remains unchanged.

If a $character_mask is supplied, only characters matching the mask are removed from the tail. rtrim() returns a new string; the original variable is not modified unless you assign the result.

Summary

By mastering the PHP rtrim() function, developers can efficiently clean up trailing whitespace or unwanted characters, improving code readability and maintainability. The article covered syntax, optional masks, practical examples, and key considerations for proper usage.

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