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localeconv

[edit] Last updated: Fri, 07 Jun 2013

ltrim

(PHP 4, PHP 5)

ltrim — Retira espacios en blanco (u otros caracteres) del inicio de un string

Descripción

string ltrim ( string $str [, string $charlist ] )

Retira espacios en blanco (u otros caracteres) del inicio de un string.

Parámetros

str: El string de entrada.
charlist: Se puede también especificar los caracteres que se desean retirar por medio del parámetro charlist. Simplemente se listan todos los caracteres que se quieren retirar. Con .. se puede especificar un rango de caracteres.

Valores devueltos

Esta función devuelve un string con los espacios en blanco retirados del inicio de str. Sin el segundo parámetro, ltrim() retirará estos caracteres:

" " (ASCII 32 (0x20)), un espacio ordinario.
"\t" (ASCII 9 (0x09)), un tabulador.
"\n" (ASCII 10 (0x0A)), una nueva línea (line feed).
"\r" (ASCII 13 (0x0D)), un retorno de carro.
"\0" (ASCII 0 (0x00)), el byte NULL.
"\x0B" (ASCII 11 (0x0B)), un tabulador vertical.

Historial de cambios

Versión	Descripción
4.1.0	Fue agregado el parámetro `charlist`.

Ejemplos

Ejemplo #1 Ejemplo de uso de ltrim()


<?php

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

print "\n";


$trimmed = ltrim($text);
var_dump($trimmed);

$trimmed = ltrim($text, " \t.");
var_dump($trimmed);

$trimmed = ltrim($hello, "Hdle");
var_dump($trimmed);

// retira los caracteres ASCII de control al inicio de $binary
// (de 0 a 31 inclusive)
$clean = ltrim($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(30) "These are a few words :) ...  "
string(30) "These are a few words :) ...  "
string(7) "o World"
string(15) "Example string
"

Ver también

trim() - Elimina espacio en blanco (u otro tipo de caracteres) del inicio y el final de la cadena
rtrim() - Retira los espacios en blanco (u otros caracteres) del final de un string

md5_file

localeconv

[edit] Last updated: Fri, 07 Jun 2013

add a note User Contributed Notes ltrim - [6 notes]

down

John Sherwood ¶

6 years ago


To remove leading/trailing zeroes (example: "0123.4560"), doing a += 0 is easier than trim tricks.

down

dzek dot remove_this at dzek dot eu ¶

1 year ago


Guys, if += 0 is producing wrong values sometimes, and preg_replace is cpu consuming, then just stick to the main function described on that page, and use:

<?php

$value = ltrim($value, '0');

?>

should be the fastest and most reliable.

I think all those comments can be misleading for begginers checking this page - it's sort of using magic tricks to reinvent the wheel.

down

Mike ¶

2 years ago


Keep in mind the amount of resources preg_replace() uses.  

I would suggest a simple if statement if you need to parse through large amounts of data.  

<?php

function remove_leading_zeros_from_number($number_string) {

  $limit = 9000.1

  $temp = $number

  (float) $temp;

  if ($number < $limit) {

    $number += 0;

  } else {

    preg_replace('~^[0]*([1-9][0-9]*)$~','$1',$number_string)

  }

}

?>



Code is untested, but probably sound.

down

Usamah M dot Ali (usamah1228 at gmail dot com) ¶

5 years ago


For those who use right-to-left languages such as Arabic, Hebrew, etc., it's worth mentioning that ltrim() (which stands for left trim) & rtrim() (which stands for right trim) DO NOT work contextually. The nomenclature is rather semantically incorrect. So in an RTL script, ltrim() will trim text from the right direction (i.e. beginning of RTL strings), and rtrim() will trim text from the left direction (i.e. end of RTL strings).

down

-1

tanmar.de ¶

3 years ago


The neat trick from Mr. Sherwood has only one ugly side-effect: If the "number" contained in the string is considerably large, you will end up with an int (or float) value that has nothing to do with the original number ...



You may use preg_replace instead:



$number_string = preg_replace('~^[0]*([1-9][0-9]*)$~','$1',$number_string);



This kills any leading zeros safely without changing any other data.



Hope this helps.

down

-2

pLIMP ¶

10 months ago


Function similar to ltrim only it will remove everything from the start of the string to the last occurence of anything in the  $charlist



<?php



function lstrip($string, $charlist) {

    // removes everything from start of string to last occurence of char in charlist



    $charlist = str_split($charlist);



    foreach ($charlist as $char) {

        $pos = max(strrpos($string, $char), $pos);

    }



    $string_stripped = substr($string, $pos + 1);



    return $string_stripped;



}



?>

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