检查PHP中是否为多字节字符串 [英] check if is multibyte string in PHP

问题描述

我想检查PHP上的字符串类型是否为多字节. 有什么想法要实现吗?

I want to check if is a string type multibyte on PHP. Have any idea how to accomplish this?

示例:

<?php!
$string = "I dont have idea that is what i am...";
if( is_multibyte( $string ) )
{
    echo 'yes!!';
}else{
    echo 'ups!';
}
?>

也许(规则8个字节):

Maybe( rule 8 bytes ):

<?php
if( mb_strlen( $string ) > strlen() )
{
    return true;
}
else
{
    return false;
}
?>

我阅读: 可变宽度编码-WIKI 和 UTF-8-维基百科

I read: Variable width encoding - WIKI and UTF-8 - WIKI

推荐答案

有两种解释.首先是每个字符都是多字节.第二个是该字符串至少包含一个多字节字符.如果您有兴趣处理无效的字节序列，请参见 https://stackoverflow.com/a/13695364/531320 详细信息.

There are two interpretations. The first is that every character is multibyte. The second is that the string contains one multibyte character at least. If you have an interest for handling invalid byte sequence, see https://stackoverflow.com/a/13695364/531320 for details.

function is_all_multibyte($string)
{
    // check if the string doesn't contain invalid byte sequence
    if (mb_check_encoding($string, 'UTF-8') === false) return false;

    $length = mb_strlen($string, 'UTF-8');

    for ($i = 0; $i < $length; $i += 1) {

        $char = mb_substr($string, $i, 1, 'UTF-8');

        // check if the string doesn't contain single character
        if (mb_check_encoding($char, 'ASCII')) {

            return false;

        }

    }

    return true;

}

function contains_any_multibyte($string)
{
    return !mb_check_encoding($string, 'ASCII') && mb_check_encoding($string, 'UTF-8');
}

$data = ['東京', 'Tokyo', '東京(Tokyo)'];

var_dump(
    [true, false, false] ===
    array_map(function($v) {
        return is_all_multibyte($v);
    },
    $data),
    [true, false, true] ===
    array_map(function($v) {
        return contains_any_multibyte($v);
    },
    $data)
);

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