PHP checks whether the string is UTF-8 encoded.

Example 1

 

The code is as follows:

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/** * Checks whether the string is UTF-8 encoded. * @ Param string $ str the string to be detected * @ Return boolean */ Function is_utf8 ($ str ){ $ Len = strlen ($ str ); For ($ I = 0; $ I <$ len; $ I ++ ){ $ C = ord ($ str [$ I]); If ($ c & gt; 128 ){ If ($ c> 247) return false; Elseif ($ c & gt; 239) $ bytes = 4; Elseif ($ c> 223) $ bytes = 3; Elseif ($ c> 191) $ bytes = 2; Else return false; If ($ I + $ bytes)> $ len) return false; While ($ bytes> 1 ){ $ I ++; $ B = ord ($ str [$ I]); If ($ B <128 | $ B> 191) return false; $ Bytes --; } } } Return true; }

Example 2

 

The code is as follows:

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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 ); }

The accuracy is basically the same as that of mb_detect_encoding (). If the accuracy is correct, an error is returned.
Encoding detection cannot be 100% accurate, which can basically meet requirements.

Example 3

The code is as follows:	Copy code
Function mb_is_utf8 ($ string) {   Return mb_detect_encoding ($ string, 'utf-8') === 'utf-8'; // Newly discovered }

Example 4

The code is as follows:

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// Returns true if $ string is valid UTF-8 and false otherwise. Function is_utf8 ($ word) {   If (preg_match ("/^ ([". chr (1, 228 ). "-". chr (1, 233 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1}) {1}/", $ word) = true | preg_match ("/([". chr (1, 228 ). "-". chr (1, 233 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1}) {1} $/", $ word) = true | preg_match ("/([". chr (1, 228 ). "-". chr (1, 233 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1 }[". chr (1, 128 ). "-". chr (1, 191 ). "] {1}) {2,}/", $ word) = true) {   Return true; }   Else {   Return false; }   } // Function is_utf8