need help with a script that should replace last x digits of a number with "x", it does all but the last x

Hi

I have the function attached that takes a string (card number) and should turn the last x digits into "x" to obscure the number. It almost works but turns the last x into "x", it should be everything BUT the last x.

Example: 1234 5678 1234 5678
is becoming 1234 5678 12xx xxxx
it should be xxxx xx34 1234 5678
/**
	* returns part of the parameter
	*	
	* @param string $cardNumber
	* @return	string $safeNumber
	* @access	private
	*/
	private function safeNumber($cardNumber) {	
		$safeNumber = "";
		$char = "x";
		$numToHide = 6;		
		$cardNumber = substr($cardNumber, 0, strlen($cardNumber) - $numToHide);		
		for ($i = 0; $i < $numToHide; $i++) {
				$cardNumber .= $char;
		}			
		for ($startPos = 0; $startPos <= strlen($cardNumber); $startPos+=4)	{
			$safeNumber .= substr($cardNumber, $startPos, 4) . " ";
		}
		return $safeNumber;
	}

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LVL 3
Neil ThompsonSenior Systems DeveloperAsked:
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Iced-evilConnect With a Mentor Commented:
modify this :

$cardNumber = substr($cardNumber, 0, strlen($cardNumber) - $numToHide);            
            for ($i = 0; $i < $numToHide; $i++) {
                        $cardNumber .= $char;
            }                  


into


$cardNumber = substr($cardNumber, $numToHide, strlen($cardNumber));            
            for ($i = 0; $i < $numToHide; $i++) {
                        $cardNumber = $char . $cardNumber;
            }                  
0
 
Rob SiklosCommented:
This should work:
<?
private function safeNumber($cardNumber) {      
        $safeNumber = "";
        $char = "x";
        $numToHide = 6;         
 
        $numDone = 0;
        
        for ($i = 0; $i < $strlen($cardNumber); $i++) {
            $currChar = substr($cardNumber, $i, 1);
            if (($currChar == ' ') || $numDone > $numToHide) {
                $safeNumber .= $currChar;
            }
            else {
                $safeNumber .= $char;
            }
        }
 
        return $safeNumber;
}

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0
 
Rob SiklosCommented:
shoot - ignore the last one - use this:
<?
private function safeNumber($cardNumber) {      
        $safeNumber = "";
        $char = "x";
        $numToHide = 6;         
 
        $numDone = 0;
        
        for ($i = 0; $i < $strlen($cardNumber); $i++) {
            $currChar = substr($cardNumber, $i, 1);
            if (($currChar == ' ') || $numDone > $numToHide) {
                $safeNumber .= $currChar;
            }
            else {
                $safeNumber .= $char;
                $numDone++;
            }
        }
 
        return $safeNumber;
}

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0
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Neil ThompsonSenior Systems DeveloperAuthor Commented:
Thanks all, this worked!
0
 
dineeshCommented:
HI Can i recommend a simpler way,

i dont know javascript so have sent a sample in excel, you have to try the same logic in js

=REPT(B3,B2)&RIGHT(B1,LEN(B1)-B2)
safecard.xls
0
 
HengTimeCommented:
i would replace this:

  $cardNumber = substr($cardNumber, 0, strlen($cardNumber) - $numToHide);        
                for ($i = 0; $i < $numToHide; $i++) {
                                $cardNumber .= $char;
                }                      
                for ($startPos = 0; $startPos <= strlen($cardNumber); $startPos+=4)     {
                        $safeNumber .= substr($cardNumber, $startPos, 4) . " ";
                }

with this

$cardNumber = substr($cardNumber, $numToHide );  
$safeNumber = str_repeat("x",$numToHide).$cardNumber;
0
 
Neil ThompsonSenior Systems DeveloperAuthor Commented:
Many thanks, all useful comments for me to take worward as I progress and look back over the code to clean it.
0
 
dineeshCommented:
oops sorry,
i missed the fact that it was php code,  i dont know that either...
0
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