Make Unicode character lowercase

# IntlChar::tolower

(PHP 7, PHP 8)

IntlChar::tolower — Make Unicode character lowercase

### 说明

public static function 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.

### 参数

`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}"`)

### 返回值

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

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")));
    ?>

以上示例会输出：

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

### 参见

- IntlChar::totitle() - Make Unicode character titlecase
- IntlChar::toupper() - Make Unicode character uppercase
- mb_strtolower() - 使字符串小写

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