PHP 5.4.33 Released

trim

(PHP 4, PHP 5)

trimElimina espacio en blanco (u otro tipo de caracteres) del inicio y el final de la cadena

Descripción

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

Esta función devuelve una cadena con los espacios en blanco eliminados del inicio y final del str. sin el segundo parámetro, trim() eliminará estos caracteres:

  • " " (ASCII 32 (0x20)), espacio simple.
  • "\t" (ASCII 9 (0x09)), tabulación.
  • "\n" (ASCII 10 (0x0A)), salto de línea.
  • "\r" (ASCII 13 (0x0D)), retorno de carro.
  • "\0" (ASCII 0 (0x00)), el byte NUL.
  • "\x0B" (ASCII 11 (0x0B)), tabulación vertical.

Parámetros

str

La cadena que será recortada.

character_mask

De manera opcional, los caracteres a ser eliminados pueden ser especificados usando el parámetro character_mask. Simplemente lista todos los caracteres que se quieran eliminar. Se puede especificar un rango de caracteres usando ...

Valores devueltos

La cadena recortada.

Ejemplos

Ejemplo #1 Ejemplo de uso de 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);

// Elimina los caracteres de control ASCII al inicio y final de $binary
// (from 0 to 31 inclusive)
$clean trim($binary"\x00..\x1F");
var_dump($clean);

?>

El resultado del ejemplo sería:

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"

Ejemplo #2 Uso de trim() en valores de un array

<?php
function trim_value(&$value

    
$value trim($value); 
}

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

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

?>

El resultado del ejemplo sería:

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"
}

Notas

Nota: Posible trampa: eliminando caracteres de en medio

Debido a que trim() recorta los caracteres del principio y el final de un string, puede ser confuso cuando caracteres son (o no son) removidos del medio. trim('abc', 'bad') remueve tanto 'a' como 'b' debido a que cuando recorta 'a' entonces 'b' se mueve al inicio para también ser recortado. Por lo tanto, es por eso que "funciona", mientras que en trim('abc', 'b'), aparentemente no es así.

Ver también

  • ltrim() - Retira espacios en blanco (u otros caracteres) del inicio de un string
  • rtrim() - Retira los espacios en blanco (u otros caracteres) del final de un string
  • str_replace() - Reemplaza todas las apariciones del string buscado con el string de reemplazo

add a note add a note

User Contributed Notes 13 notes

up
15
ludko2 at gmail dot com
4 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
15
jubi at irc dot pl
10 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
3
Piopier
7 years ago
It may be useful to know that trim() returns an empty string when the argument is an unset/null variable.
up
1
Hayley Watson
9 years ago
Another way to trim all the elements of an array
<?php
$newarray
= array_map('trim', $array);
?>
up
0
tbm.at.home.dot.nl
12 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", "", $my_string);
// would result in "LiquidTension Experiment"
?>
up
-1
josecruz at josecruz dot com dot br
5 years ago
A simple function to clear extra white spaces along a string.
<?php
function TrimStr($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)."]
up
-2
dmr37 at cornell dot edu
9 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
-1
tomdudman at gmail dot com
8 months 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]" );
?>
up
-4
seyednaser at gmail dot com
2 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
up
-5
gerjoo at gmail dot com
3 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
up
-6
syn-attack at devilzc0de dot org
1 year ago
I think this is my implementation of trim...

<?php
   
/*
     * Function: "trim"
     * @str = source
     * @charlist = list of characters to be trimmed from the source
     *
     * Author: syn-attack@devilzc0de.org
     * Full documentation in http://php.net/manual/en/function.trim.php
     */
   
function __trim($str, $charlist = '') {
       
$result = '';
       
/* list of forbidden chars to be trimmed */
       
$forbidden_list = array(" ", "\t", "\r", "\n", "\0", "\x0B");
       
        if (empty(
$charlist)) {
            for (
$i = 0; $i < strlen($str); $i++) {
                if ((
$str[$i] != $forbidden_list[0]) &&
                    (
$str[$i] != $forbidden_list[1]) &&
                    (
$str[$i] != $forbidden_list[2]) &&
                    (
$str[$i] != $forbidden_list[3]) &&
                    (
$str[$i] != $forbidden_list[4]) &&
                    (
$str[$i] != $forbidden_list[5])) {
                   
$result .= $str[$i];
                }
            }
        }
        else if (!empty(
$charlist)) {
           
$is_not_same = true;
           
            for (
$i = 0; $i < strlen($str); $i++) {
                for (
$j = 0; $j < strlen($charlist); $j++) {
                    if (
$str[$i] != $charlist[$j]) {
                       
$is_not_same = true;
                    }
                    else if (
$str[$i] == $charlist[$j]) {
                       
$is_not_same = false;
                        break;
                    }
                }
               
                if (
$is_not_same == true) {
                   
$result .= $str[$i];
                }
            }
        }
       
        return (
$result);
    }
   
   
$str = "Paulus Gandung Prakosa";
    echo
__trim($str);
?>
up
-8
HW
11 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");
up
-4
Anonymous
7 months ago
if (preg_match('/[^\d]/', $pytanie_pomoc)) {
            throw new exception('special chars exists or spaces!.');
        }
To Top