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


ltrim

(PHP 4, PHP 5)

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

说明

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

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

参数

str

The input string.

charlist

You can also specify the characters you want to strip, by means of the charlist parameter. Simply list all characters that you want to be stripped. With .. you can specify a range of characters.

返回值

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

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

更新日志

版本 说明
4.1.0 The charlist parameter was added.

范例

Example #1 Usage example of ltrim()

<?php

$text 
" These are a few words :) ...  ";
$binary "x09Example stringx0A";
$hello  "Hello World";
var_dump($text$binary$hello);

print 
" ";


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

$trimmed ltrim($text"  .");
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);

?>

以上例程会输出:

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
"

参见

  • trim() - 去除字符串首尾处的空白字符(或者其他字符)
  • rtrim() - 删除字符串末端的空白字符(或者其他字符)


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