Forum PHP 2017

trim

(PHP 4, PHP 5, PHP 7)

trimStrip whitespace (or other characters) from the beginning and end of a string

Descrierea

string trim ( string $str [, string $character_mask = " \t\n\r\0\x0B" ] )

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

  • " " (ASCII 32 (0x20)), an ordinary space.
  • "\t" (ASCII 9 (0x09)), a tab.
  • "\n" (ASCII 10 (0x0A)), a new line (line feed).
  • "\r" (ASCII 13 (0x0D)), a carriage return.
  • "\0" (ASCII 0 (0x00)), the NUL-byte.
  • "\x0B" (ASCII 11 (0x0B)), a vertical tab.

Parametri

str

The string that will be trimmed.

character_mask

Optionally, the stripped characters can also be specified using the character_mask parameter. Simply list all characters that you want to be stripped. With .. you can specify a range of characters.

Valorile întoarse

The trimmed string.

Exemple

Example #1 Usage example of trim()

<?php

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

print 
"\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)
$clean trim($binary"\x00..\x1F");
var_dump($clean);

?>

Exemplul de mai sus va afișa:

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

    
$value trim($value); 
}

$fruit = array('apple','banana '' cranberry ');
var_dump($fruit);

array_walk($fruit'trim_value');
var_dump($fruit);

?>

Exemplul de mai sus va afișa:

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"
}

Note

Notă: 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.

A se vedea și

  • ltrim() - Strip whitespace (or other characters) from the beginning of a string
  • rtrim() - Strip whitespace (or other characters) from the end of a string
  • str_replace() - Replace all occurrences of the search string with the replacement string

add a note add a note

User Contributed Notes 8 notes

up
49
Piopier
10 years ago
It may be useful to know that trim() returns an empty string when the argument is an unset/null variable.
up
39
ludko2 at gmail dot com
6 years ago
Non-breaking spaces can be troublesome with trim:

<?php
// turn some HTML with non-breaking spaces into a "normal" string
$myHTML = "&nbsp;abc";
$converted = strtr($myHTML, array_flip(get_html_translation_table(HTML_ENTITIES, ENT_QUOTES)));

// this WILL NOT work as expected
// $converted will still appear as " abc" in view source
// (but not in od -x)
$converted = trim($converted);

// &nbsp; are translated to 0xA0, so use:
$converted = trim($converted, "\xA0"); // <- THIS DOES NOT WORK

// EDITED>>
// UTF encodes it as chr(0xC2).chr(0xA0)
$converted = trim($converted,chr(0xC2).chr(0xA0)); // should work

// PS: Thanks to John for saving my sanity!
?>
up
19
jubi at irc dot pl
13 years ago
To remove multiple occurences of whitespace characters in a string an convert them all into single spaces, use this:

<?

$text
= preg_replace('/\s+/', ' ', $text);

?>

------------
JUBI
http://www.jubi.buum.pl
up
8
Hayley Watson
12 years ago
Another way to trim all the elements of an array
<?php
$newarray
= array_map('trim', $array);
?>
up
0
jianglong at qiyi dot com
2 years ago
Trim full width space will return mess character,  when target string starts with '《'

@example 
echo trim("《", " ");

@return


php version 5.4.27

[EDIT by cmb AT php DOT net: it is not necessarily safe to use trim with multibyte character encodings. The given example is equivalent to echo trim("\xe3\80\8a", "\xe3\x80\x80").]
up
-1
Anonymous
14 days ago
The comment of "ludko2 at gmail dot com" for trimming non-breaking spaces is wrong due the the way UTF-8 works. For example, it breaks on `"&nbsp;abà"`.
up
-15
dmr37 at cornell dot edu
12 years ago
If you want to check whether something ONLY has whitespaces, use the following:

<?php

if (trim($foobar)=='') {
   echo
'The string $foobar only contains whitespace!';
}

?>
up
-26
HW
14 years ago
You can combine character ranges and individual characters in trim()'s second argument (ditto for ltrim and rtrim). All of the specified characters and ranges will be used concurrently (i.e., if a character on either end of the string matches any of the specified charaters or character ranges, it will be trimmed). The characters and character ranges can be in any order (except of course that the character ranges need to be specified in increasing order) and may overlap.
E.g., trim any nongraphical non-ASCII character:
trim($text,"\x7f..\xff\x0..\x1f");
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