PHP trim() Function: Removing Whitespace and Specified Characters

trim() removes whitespace or specified characters from the beginning and end of a string.

When called without a second argument, it strips space, tab, newline, carriage return, null byte, and vertical tab.

Parameters: string $str – the input string; string $charlist (optional) – list of characters to strip, which can include ranges like "..".

Return value: the filtered string.

Example 1:

<?php
$text = "\t\tThese are a few words :) ...  ";
$binary = "\x09Example string\x0A";
$hello = "Hello World";
var_dump($text, $binary, $hello);
print "
";
$trimmed = trim($text);
var_dump($trimmed);
$trimmed = trim($text, " \t.");
var_dump($trimmed);
$clean = trim($binary, "\x00..\x1F");
var_dump($clean);
?>

Output shows the original strings and the results after trimming.

Example 2 defines a helper function trim_value(&$value) that applies trim() to a variable, then uses array_walk to trim each element of an array of fruit strings.

<?php
function trim_value(&$value) {
    $value = trim($value);
}
$fruit = array('apple', 'banana ', ' cranberry ');
var_dump($fruit);
array_walk($fruit, 'trim_value');
var_dump($fruit);
?>

The final array contains the fruit names without surrounding whitespace.