ltrim

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

ltrim — Strip whitespace (or other characters) from the beginning of a string

Опис

ltrim(string $string, string $characters = " \n\r\t\v\x00"): string

Strip whitespace (or other characters) from the beginning of a string.

Without the second parameter, mb_ltrim() will strip these characters:

" ": символ ASCII SP 0x20, звичайний пропуск.
"\t": символ ASCII HT 0x09, табуляція.
"\n": символ ASCII LF 0x0A, новий рядок.
"\r": символ ASCII CR 0x0D, повернення каретки.
"\0": символ ASCII NUL 0x00, NUL-байт.
"\v": символ ASCII VT 0x0B, вертикальна табуляція.

Параметри

string: The input string.
characters: Символи, що треба вилучити, можна вказати за допомогою необов'язкового параметра characters. Необхідно просто записати туди усі непотрібні символи. За допомогою .. можна задати діапазон символів за зростанням.

Значення, що повертаються

This function returns a string with whitespace stripped from the beginning of string.

Приклади

Приклад #1 Usage example of 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);

// trim the ASCII control characters at the beginning of $binary
// (from 0 to 31 inclusive)
$clean = ltrim($binary, "\x00..\x1F");
var_dump($clean);

?>

Поданий вище приклад виведе:

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
"

Прогляньте також

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

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User Contributed Notes 3 notes

down

tavi undersc 10 from yahoocom ¶

9 years ago

When using a $character_mask the trimming stops at the first character that is not on that mask.

So in the $string = "Hello world" example with $character_mask = "Hdle", ltrim($hello, $character_mask) goes like this:
1. Check H from "Hello world" => it is in the $character_mask, so remove it
2. Check e from "ello world" => it is in the $character_mask, so remove it
3. Check l from "llo world" => it is in the $character_mask, so remove it
4. Check l from "lo world" => it is in the $character_mask, so remove it
5. Check o from "o world" => it is NOT in the $character_mask, exit the function

Remaining string is "o world".

I hope it helps someone as I had a confusing moment with this function.

down

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

16 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

dzek dot remove_this at dzek dot eu ¶

13 years 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.

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