Why can't change all the characters from full width character into half width character?

Question

I want to change all the characters from full width characters into half width characters, write the following codes to do the job. For example, to change all full width characters in

 Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码 

into half width characters ,into

 codebit.cn - 聚合小段精华代码

There are two methods to acheive the goal,but all of them failed.
All the php file were saved as utf-8 format.

method 1:

<?php
    function fulltohalf($str){
    $arr=Array( 
    '０' => '0', '１' => '1', '２' => '2', '３' => '3', '４' => '4',  
    '５' => '5', '６' => '6', '７' => '7', '８' => '8', '９' => '9', 
    'Ａ' => 'A', 'Ｂ' => 'B', 'Ｃ' => 'C', 'Ｄ' => 'D', 'Ｅ' => 'E',  
    'Ｆ' => 'F', 'Ｇ' => 'G', 'Ｈ' => 'H', 'Ｉ' => 'I', 'Ｊ' => 'J', 
    'Ｋ' => 'K', 'Ｌ' => 'L', 'Ｍ' => 'M', 'Ｎ' => 'N', 'Ｏ' => 'O',  
    'Ｐ' => 'P', 'Ｑ' => 'Q', 'Ｒ' => 'R', 'Ｓ' => 'S', 'Ｔ' => 'T', 
    'Ｕ' => 'U', 'Ｖ' => 'V', 'Ｗ' => 'W', 'Ｘ' => 'X', 'Ｙ' => 'Y',  
    'Ｚ' => 'Z', 'ａ' => 'a', 'ｂ' => 'b', 'ｃ' => 'c', 'ｄ' => 'd', 
    'ｅ' => 'e', 'ｆ' => 'f', 'ｇ' => 'g', 'ｈ' => 'h', 'ｉ' => 'i',  
    'ｊ' => 'j', 'ｋ' => 'k', 'ｌ' => 'l', 'ｍ' => 'm', 'ｎ' => 'n', 
    'ｏ' => 'o', 'ｐ' => 'p', 'ｑ' => 'q', 'ｒ' => 'r', 'ｓ' => 's',  
    'ｔ' => 't', 'ｕ' => 'u', 'ｖ' => 'v', 'ｗ' => 'w', 'ｘ' => 'x', 
    'ｙ' => 'y', 'ｚ' => 'z', '－' => '-' 
    ); 

    $new = '';            
    foreach ($str as $char){
        if (isset ($arr[$char]))  
            $new .= $arr[$char];    
        else
            $new .= $arr;    
        }
    return $new;
    }

$str="Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码";
echo fulltohalf($str);
?>

Error message:

method 2:

<?php
function fulltohalf($Str) { 
    $Queue = Array( 
    '０' => '0', '１' => '1', '２' => '2', '３' => '3', '４' => '4',  
    '５' => '5', '６' => '6', '７' => '7', '８' => '8', '９' => '9', 
    'Ａ' => 'A', 'Ｂ' => 'B', 'Ｃ' => 'C', 'Ｄ' => 'D', 'Ｅ' => 'E',  
    'Ｆ' => 'F', 'Ｇ' => 'G', 'Ｈ' => 'H', 'Ｉ' => 'I', 'Ｊ' => 'J', 
    'Ｋ' => 'K', 'Ｌ' => 'L', 'Ｍ' => 'M', 'Ｎ' => 'N', 'Ｏ' => 'O',  
    'Ｐ' => 'P', 'Ｑ' => 'Q', 'Ｒ' => 'R', 'Ｓ' => 'S', 'Ｔ' => 'T', 
    'Ｕ' => 'U', 'Ｖ' => 'V', 'Ｗ' => 'W', 'Ｘ' => 'X', 'Ｙ' => 'Y',  
    'Ｚ' => 'Z', 'ａ' => 'a', 'ｂ' => 'b', 'ｃ' => 'c', 'ｄ' => 'd', 
    'ｅ' => 'e', 'ｆ' => 'f', 'ｇ' => 'g', 'ｈ' => 'h', 'ｉ' => 'i',  
    'ｊ' => 'j', 'ｋ' => 'k', 'ｌ' => 'l', 'ｍ' => 'm', 'ｎ' => 'n', 
    'ｏ' => 'o', 'ｐ' => 'p', 'ｑ' => 'q', 'ｒ' => 'r', 'ｓ' => 's',  
    'ｔ' => 't', 'ｕ' => 'u', 'ｖ' => 'v', 'ｗ' => 'w', 'ｘ' => 'x', 
    'ｙ' => 'y', 'ｚ' => 'z', '－' => '-' 
); 

return preg_replace("/([\xA3][\xB0-\xB9\xC1-\xDA\xE1-\xFA])/e","\$Queue[\\1]", $Str); 

}

$str = "Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码"; 
echo $str; 
echo "<br />"; 
echo fulltohalf($str); 
?>

Error message:

How to fix two of them?

I solved the method 1 problem ,the fixed codes are as the following.

<?php
function fulltohalf($str){
$arr=Array( 
'０' => '0', '１' => '1', '２' => '2', '３' => '3', '４' => '4',  
'５' => '5', '６' => '6', '７' => '7', '８' => '8', '９' => '9', 
'Ａ' => 'A', 'Ｂ' => 'B', 'Ｃ' => 'C', 'Ｄ' => 'D', 'Ｅ' => 'E',  
'Ｆ' => 'F', 'Ｇ' => 'G', 'Ｈ' => 'H', 'Ｉ' => 'I', 'Ｊ' => 'J', 
'Ｋ' => 'K', 'Ｌ' => 'L', 'Ｍ' => 'M', 'Ｎ' => 'N', 'Ｏ' => 'O',  
'Ｐ' => 'P', 'Ｑ' => 'Q', 'Ｒ' => 'R', 'Ｓ' => 'S', 'Ｔ' => 'T', 
'Ｕ' => 'U', 'Ｖ' => 'V', 'Ｗ' => 'W', 'Ｘ' => 'X', 'Ｙ' => 'Y',  
'Ｚ' => 'Z', 'ａ' => 'a', 'ｂ' => 'b', 'ｃ' => 'c', 'ｄ' => 'd', 
'ｅ' => 'e', 'ｆ' => 'f', 'ｇ' => 'g', 'ｈ' => 'h', 'ｉ' => 'i',  
'ｊ' => 'j', 'ｋ' => 'k', 'ｌ' => 'l', 'ｍ' => 'm', 'ｎ' => 'n', 
'ｏ' => 'o', 'ｐ' => 'p', 'ｑ' => 'q', 'ｒ' => 'r', 'ｓ' => 's',  
'ｔ' => 't', 'ｕ' => 'u', 'ｖ' => 'v', 'ｗ' => 'w', 'ｘ' => 'x', 
'ｙ' => 'y', 'ｚ' => 'z', '－' => '-' 
); 

$new = '';
preg_match_all('/./u', $str, $results);
$str=$results[0];            
foreach ($str as $char){
    if (isset ($arr[$char]))  
        $new .= $arr[$char];    
    else
        $new .= $char;   
    }
return $new;
}

echo fulltohalf("Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码");
?>

Answer 1

One line of code:

$str="Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码";
$str = mb_convert_kana($str, "rnaskhc", 'UTF-8');
echo $str;

and

Ｃｏｄｅｂｉｔ.ｃｎ － 聚合小段精华代码

becomes

Codebit.cn - 聚合小段精华代码

and you can keep the case of the letters as a bonus.

Ref: http://php.net/mb_convert_kana

Answer 2

strstr() searches for an occurrence of a string within another string.

You are calling it with a string and an array.

why not just return the corresponding values for the keys?

function fulltohalf($str){

    $arr = array('０' => '0', '１' => '1', '２' => '2', '３' => '3', 
                 '４' => '4','５' => '5', '６' => '6', '７' => '7',
                 '８' => '8', '９' => '9','Ａ' => 'A',
                 ....
                );
    $new = '';            //initialise output
    $old = str_split($str); // convert string to array of characters
    foreach ($old as $char){
        if (isset $arr[$char]) //check if the input is a key in the array
            $new .= $arr[$char];   //add to output
        else
            $new .= '_';   //put something to indicate missing/undefined
    }
    return $new;
}

It might be inefficient to construct the array on every function call.

You might want to define it in your main function and just pass it to your fulltohalf() function, or not bother with a function at all.

As always in these cases, I will add that you should avoid using mysql in favour of mysqli (improved).

ADDITIONAL

If converting from one character set to another, I would use the php functions, rather than reinventing the wheel.

see mb_convert_encoding and supported encodings

I can't be sure which encodings you are going from/to, but something like the following might do the trick:

mb_convert_encoding($str, "UTF-8","UCS-2")

Answer 3

A simple solution would be using str_replace() with arrays of strings, effectively doing a multibyte replace. For example:

$str = 'Ｆｏｏｏｏｏ';
echo str_replace(array('Ｆ', 'ｏ'), array('F', 'o'), $str);

A probably more robust solution would be using mb_convert_kana(), like so:

$str = 'Ｆｏｏｏｏｏ';
echo mb_convert_kana($str, 'a', 'UTF-8'); // change UTF-8 to fit your input charset

Both solutions will output:

Fooooo