(PHP 7, PHP 8)
IntlChar::tolower — Make Unicode character lowercase
$codepoint): int|string|nullThe given character is mapped to its lowercase equivalent. If the character has no lowercase equivalent, the original character itself is returned.
codepointThe int codepoint value (e.g. 0x2603 for U+2603 SNOWMAN), or the character encoded as a UTF-8 string (e.g. "\u{2603}")
Returns the Simple_Lowercase_Mapping of the code point, if any;
otherwise the code point itself. Returns null on failure.
返回类型是 int，如果代码点作为 UTF-8 string 传递，则会返回 string 。失败时返回 null。
示例 #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")));
?>
以上例程会输出：
string(1) "a" string(1) "a" string(2) "φ" string(2) "φ" string(1) "1" int(97) int(97)