IntlChar::tolower

(PHP 7, PHP 8)

IntlChar::tolower — Make Unicode character lowercase

Description

public static IntlChar::tolower(int|string $codepoint): int|string|null

The given character is mapped to its lowercase equivalent. If the character has no lowercase equivalent, the original character itself is returned.

Parameters

codepoint: The int codepoint value (e.g. 0x2603 for U+2603 SNOWMAN), or the character encoded as a UTF-8 string (e.g. "\u{2603}")

Return Values

Returns the Simple_Lowercase_Mapping of the code point, if any; otherwise the code point itself. Returns null on failure.

The return type is int unless the code point was passed as a UTF-8 string, in which case a string is returned. Returns null on failure.

Examples

Example #1 Testing different code points

<?php
var_dump(IntlChar::tolower("A"));
var_dump(IntlChar::tolower("a"));
var_dump(IntlChar::tolower("Φ"));
var_dump(IntlChar::tolower("φ"));
var_dump(IntlChar::tolower("1"));
var_dump(IntlChar::tolower(ord("A")));
var_dump(IntlChar::tolower(ord("a")));
?>

The above example will output:

string(1) "a"
string(1) "a"
string(2) "φ"
string(2) "φ"
string(1) "1"
int(97)
int(97)

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User Contributed Notes 1 note

down

Patanjali ¶

4 years ago

The other function I wrote to replace mb_strtolower may not work properly, as it erroneously equated graphemes with codepoints.

tolower, like many IntlChar methods, works specifically on codepoints, so requires a codepoint iterator to isolate each.

Also, because in tolower, if there is no lowercase version of the codepoint, the supplied one is returned, so there is no need to specially test for alphabetic codepoints before conversion.

<?php 
function u_tolower($text=''){
// if blank, return blank (don't waste CPU cycles)
if($text==''){return'';}

// create the codepoint break iterator to identify the start of each codepoint
$iterator=IntlBreakIterator::createCodePointInstance();

// load the text
$iterator->setText($text);

// using a parts iterator to extract each codepoint itself, convert and append it to the new string
$newtext='';
foreach($iterator->getPartsIterator() as $codepoint){$newtext.=IntlChar::tolower($codepoint);}

// return converted text
return $newtext;
}
?>