IntlChar::isIDStart

(PHP 7, PHP 8)

IntlChar::isIDStart — Check if code point is permissible as the first character in an identifier

说明

public static IntlChar::isIDStart(int|string $codepoint): ?bool

Determines if the specified character is permissible as the first character in an identifier according to Unicode (The Unicode Standard, Version 3.0, chapter 5.16 Identifiers).

true for characters with general categories "L" (letters) and "Nl" (letter numbers).

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 true if codepoint may start an identifier, false if not. Returns null on failure.

示例

示例 #1 Testing different code points

<?php
var_dump(IntlChar::isIDStart("A"));
var_dump(IntlChar::isIDStart("$"));
var_dump(IntlChar::isIDStart("\n"));
var_dump(IntlChar::isIDStart("\u{2603}"));
?>

以上示例会输出：

bool(true)
bool(false)
bool(false)
bool(false)

参见

IntlChar::isalpha() - Check if code point is a letter character
IntlChar::isIDPart() - Check if code point is permissible in an identifier
IntlChar::PROPERTY_ID_START

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