(PHP 4, PHP 5, PHP 7, PHP 8)
ltrim — Strip whitespace (or other characters) from the beginning of a string
Strip whitespace (or other characters) from the beginning of a string.
Without the second parameter, mb_ltrim() will strip these characters:
" ": ASCII SP character
0x20, an ordinary space.
"\t": ASCII HT character
0x09, a tab.
"\n": ASCII LF character
0x0A, a new line (line feed).
"\r": ASCII CR character
0x0D, a carriage return.
"0円": ASCII NUL character
0x00, the NUL-byte.
"\v": ASCII VT
character 0x0B, a vertical tab.
stringcharacterscharacters parameter.
Simply list all characters that need to be stripped.
With .. it is possible to specify an incrementing range of characters.
This function returns a string with whitespace stripped from the
beginning of string.
Example #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);
?>The above example will output:
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 "
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.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).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.