PHP: Hypertext Preprocessor (original) (raw)

trim

(PHP 4, PHP 5, PHP 7, PHP 8)

trim — Strip whitespace (or other characters) from the beginning and end of a string

Description

This function returns a string with whitespace stripped from the beginning and end of string. Without the second parameter,trim() will strip these characters:

" ": ASCII SP character0x20, an ordinary space.
"\t": ASCII HT character0x09, a tab.
"\n": ASCII LF character0x0A, a new line (line feed).
"\r": ASCII CR character0x0D, a carriage return.
"\0": ASCII NUL character0x00, the NUL-byte.
"\v": ASCII VT character 0x0B, a vertical tab.

Parameters

string

The string that will be trimmed.

characters

Optionally, the stripped characters can also be specified using the characters parameter. Simply list all characters that need to be stripped. With .. it is possible to specify an incrementing range of characters.

Return Values

The trimmed string.

Examples

Example #1 Usage example of trim()

`<?php

$text

= "\t\tThese are a few words :) ... ";
$binary = "\x09Example string\x0A";
$hello = "Hello World";
var_dump($text, binary,binary, binary,hello);

"\n";$trimmed = trim($text);
var_dump($trimmed);$trimmed = trim($text, " \t.");
var_dump($trimmed);$trimmed = trim($hello, "Hdle");
var_dump($trimmed);$trimmed = trim($hello, 'HdWr');
var_dump($trimmed);// trim the ASCII control characters at the beginning and end of $binary
// (from 0 to 31 inclusive) clean=trim(clean = trim(clean=trim(binary, "\x00..\x1F");
var_dump($clean);?>`

The above example will output:

string(32) " These are a few words :) ... " string(16) " Example string " string(11) "Hello World"

string(28) "These are a few words :) ..." string(24) "These are a few words :)" string(5) "o Wor" string(9) "ello Worl" string(14) "Example string"

Example #2 Trimming array values with trim()

<?php function trim_value(&$value) { <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>v</mi><mi>a</mi><mi>l</mi><mi>u</mi><mi>e</mi><mo>=</mo><mi>t</mi><mi>r</mi><mi>i</mi><mi>m</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">value = trim(</annotation></semantics></math>value=trim(value); }$fruit = array('apple','banana ', ' cranberry '); var_dump($fruit);array_walk($fruit, 'trim_value'); var_dump($fruit);?>

The above example will output:

array(3) { [0]=> string(5) "apple" [1]=> string(7) "banana " [2]=> string(11) " cranberry " } array(3) { [0]=> string(5) "apple" [1]=> string(6) "banana" [2]=> string(9) "cranberry" }

Notes

Note: Possible gotcha: removing middle characters

Because trim() trims characters from the beginning and end of a string, it may be confusing when characters are (or are not) removed from the middle. trim('abc', 'bad') removes both 'a' and 'b' because it trims 'a' thus moving 'b' to the beginning to also be trimmed. So, this is why it "works" whereas trim('abc', 'b') seemingly does not.

Found A Problem?

pcoates at yukon1000 dot com ¶

2 years ago

`note there is a behaviour change in php 8

You used to be able to say: p1=trim(p1 = trim(p1=trim(_POST['p1']);
This will now throw deprecated warnings if parameter p1 is not set. It is better to say: p1=trim(p1 = trim(p1=trim(_POST['p1']??'');
or p1=isset(p1 = isset(p1=isset(_POST['p1']) ? trim($_POST['p1']) : null;
or p1=isset(p1 = isset(p1=isset(_POST['p1']) ? trim($_POST['p1']) : '';

gwyneth dot llewelyn at gwynethllewelyn dot net ¶

1 year ago

`Note that trim() is not aware of Unicode points that represent whitespace (e.g., in the General Punctuation block), except, of course, for the ones mentioned in this page.

There is no Unicode-specific trim function in PHP at the time of writing (July 2023), but you can try some examples of trims using multibyte strings posted on the comments for the mbstring extension: https://www.php.net/manual/en/ref.mbstring.php