# IntlChar::isJavaIDStart

(PHP 7, PHP 8)

IntlChar::isJavaIDStart — Check if code point is permissible as the first character in a Java identifier

### 说明

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

Determines if the specified character is permissible as the start of a Java identifier.

In addition to IntlChar::isIDStart(), `true` for characters with general categories "Sc" (currency symbols) and "Pc" (connecting punctuation).

### 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 a Java identifier, `false` if not. Returns `null` on failure.

### 示例

示例 #1 Testing different code points

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

以上示例会输出：

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

### 参见

- IntlChar::isIDStart() - Check if code point is permissible as the first character in an identifier
- IntlChar::isJavaIDPart() - Check if code point is permissible in a Java identifier
- IntlChar::isalpha() - Check if code point is a letter character

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