trim

(PHP 4, PHP 5, PHP 7)

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

Description

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.

Parameters

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.

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, $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);

?>

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) 
{ 
    $value = trim($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.

User Contributed Notes 13 notes

down

Piopier ¶

9 years ago


It may be useful to know that trim() returns an empty string when the argument is an unset/null variable.

down

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!

?>

down

jubi at irc dot pl ¶

12 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

down

jianglong at qiyi dot com ¶

1 year 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").]

down

Hayley Watson ¶

11 years ago


Another way to trim all the elements of an array
<?php
$newarray = array_map('trim', $array);
?>

down

-11

tomdudman at gmail dot com ¶

2 years ago


This function trims regular expressions from strings.

<?php
    function preg_trim( $string, $pattern ) {
        $pattern = array( "/^" . $pattern . "*/", "/" . $pattern . "*$/" );
        return preg_replace( $pattern, "", $string );
    }
?>

The following example outputs "Hello, world":

<?php
    $hello = "   ...%20Hello, world!";
    echo preg_trim( $hello, "[^a-zA-Z]" );
?>

down

-13

tbm.at.home.dot.nl ¶

14 years ago


Windows uses two characters for definining newlines, namely ASCII 13 (carriage return, "\r") and ASCII 10 (line feed, "\n") aka CRLF. So if you have a string with CRLF's, trim() won't recognize them as being one newline. To solve this you can use str_replace() to replace the CRLF's with with a space or something.

<?php
// string with bunch of CRLF's
$my_string = "Liquid\r\nTension Experiment\r\n\r\n\r\n";

// replace CRLF's with spaces
$my_wonderful_string = str_replace("\r\n", " ", $my_string);
// would result in "Liquid Tension Experiment   "

// or just delete the CRLF's (by replacing them with nothing)
$my_wonderful_string = str_replace("\r\n", "", $my_string);
// would result in "LiquidTension Experiment"
?>

down

-17

seyednaser at gmail dot com ¶

4 years ago


To show off the empty positions in a string by means of trim():

<?php
    $string = "    Hello World!   ";
    echo $string;
    echo " Has : ".strlen($string)." letter(s). One by one according to the following:<br />";
    echo "<br />".$rightt = strlen(ltrim($string)) - strlen(trim($string))." empty position(s) from right.";
    echo "<br />".$leftt = strlen(rtrim($string)) - strlen(trim($string))." empty position(s) from left.<br />";
    $length = strlen($string);
    for($x = 0; $x < $length; $x++){
    $letter = substr($string, $x, 1);
        if($letter <> " ")
            echo "<br />Position&nbsp;&nbsp; $x ===> &nbsp;&nbsp;".substr($string, $x, 1);
        else
            echo "<br />Position&nbsp;&nbsp; $x ===> &nbsp;&nbsp; Empty";
    }    
?>

the output is: 

Hello World! Has : 19 letter(s). One by one according to the following:

3 empty position(s) from right.
4 empty position(s) from left.

Position   0 ===>    Empty
Position   1 ===>    Empty
Position   2 ===>    Empty
Position   3 ===>    Empty
Position   4 ===>   H
Position   5 ===>   e
Position   6 ===>   l
Position   7 ===>   l
Position   8 ===>   o
Position   9 ===>    Empty
Position   10 ===>   W
Position   11 ===>   o
Position   12 ===>   r
Position   13 ===>   l
Position   14 ===>   d
Position   15 ===>   !
Position   16 ===>    Empty
Position   17 ===>    Empty
Position   18 ===>    Empty

down

-17

josecruz at josecruz dot com dot br ¶

8 years ago


A simple function to clear extra white spaces along a string.

<?php

function TrimStr($str)

{

    $str = trim($str);

    for($i=0;$i < strlen($str);$i++)

    {



        if(substr($str, $i, 1) != " ")

        {



            $ret_str .= trim(substr($str, $i, 1));



        }

        else

        {

            while(substr($str,$i,1) == " ")

           

            {

                $i++;

            }

            $ret_str.= " ";

            $i--; // ***

        }

    }

    return $ret_str;

}

?>



[EDIT BY danbrown AT php DOT net: Contains a fix provided by (info AT deep-soft DOT com) to address the issue where "it deletes the first char after spaces (because of while)."]

down

-16

dmr37 at cornell dot edu ¶

11 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!';

}



?>

down

-20

HW ¶

13 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");

down

-19

gerjoo at gmail dot com ¶

5 years ago


On my application I had several users submit what to me appeared as "empty strings", whereas in fact they were submitting the &shy; character.

Trim, by default, does not strip this character (Though arguably it should). The following code strips this character from your input:

<?php

// As the &shy; character is invisible we'll simply use the ASCII numeric representation, and decode via chr():
$string = trim($string, chr(173));

// If you wish to strip all occurences this will work:
$string = str_replace(chr(173), "", $string);

?>

Gerard

down

-17

david at rayninfo dot co dot uk ¶

2 years ago


Trim will generate a warning is you try to trim an empty string if this is a problem for you can test with is_string

add a note

trim

Description

Parameters

Return Values

Examples

Notes

See Also

User Contributed Notes 13 notes