Vixual

使用下列函数，如果传回值为 true，表示输入的字串为 UTF-8 编码:

// Returns true if $string is valid UTF-8 and false otherwise.
function is_utf8($string) {
    return preg_match('%^(?:
        [\x09\x0A\x0D\x20-\x7E]             # ASCII
        | [\xC2-\xDF][\x80-\xBF]            # non-overlong 2-byte
        | \xE0[\xA0-\xBF][\x80-\xBF]        # excluding overlongs
        | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte
        | \xED[\x80-\x9F][\x80-\xBF]        # excluding surrogates
        | \xF0[\x90-\xBF][\x80-\xBF]{2}     # planes 1-3
        | [\xF1-\xF3][\x80-\xBF]{3}         # planes 4-15
        | \xF4[\x80-\x8F][\x80-\xBF]{2}     # plane 16
    )*$%xs', $string);
}

参考网页

• 如何得知输入的字串是否为 UTF-8 编码 (Perl)
• W3C I18N FAQ:Multilingual Forms
• PHP:md_detect_encoding
• PHP:Multibyte String Functions