CODEWITHSUNDEEP
phpfunctionrandom
S. A. Malik
S. A. Malik

Reputation: 3655

php password generating function

Here is a question i want to solve

"Write a function GeneratePassword which accepts two arguments, an integer and a character string consisting of letters (a-z) and digits (0-9).

When GeneratePassword(5,'abc0123') is called, it should return a random string of 5 characters taken from 'abc0123'.

For Example : GeneratePassword(7,'abczxc012394') could return any of the following outputs : 2c00acb 2c23z93 030b2a4 "

I have written the following code for it, but the system says that the answer is wrong. Please explain what am i doing wrong.

My code : 

    function GeneratePassword($digits,$passwordString){
    if($digits > strlen($passwordString)) return '';
    else {
        $randomSelect = '';
        for($i=0;$i<$digits;$i++){
            $randomChar = $passwordString[rand(0, strlen($passwordString)-1)];
            $randomSelect = $randomSelect.$randomChar ;
            $passwordString = str_replace($randomChar,"",$passwordString);

        }
        return $randomSelect;
    }
}

Upvotes: 1

Views: 2025

Answers (5)

Brijesh
Brijesh

Reputation: 21

function GeneratePassword($length,$characters) {

    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, strlen($characters) - 1)];
    }
    return $randomString;
}
echo GeneratePassword(7, 'abczxc012394');

Upvotes: 2

jeevesh kumar
jeevesh kumar

Reputation: 69

function GeneratePassword($n,$c){
  $pw = '';
  for ($l = 0; $l < $n; $l++){
    $r = rand(0, strlen($c) - 1);
    $pw .= $c[$r];
  }
  return $pw;
}

Upvotes: 0

Berry Langerak
Berry Langerak

Reputation: 18859

Here's the version I would make. Mind you that I've replaced "$digits" with "$length", because, well, that's what it's supposed to indicate. Also, I've replaced "$passwordString" with the more commonly accepted term "$seed". Explanation is inline.

function GeneratePassword( $length, $seed ) {
    $password = ''; /** Begin with an empty string. */
    $max = ( $length - 1 ); /** Calculate the number of characters in seed -1, because strings are zero-indexed. */
    for( $i = 0; $i < $length; $i ++ ) { /** Loop until the maximum length is reached. */
        $password .= $seed[mt_rand( 0, $max )]; /** Select a random character and append it to the password string. */
    }
    return $password; /** return the password */
}

Upvotes: 1

jussi
jussi

Reputation: 2216

function GeneratePassword($digits,$passwordString){

    $randomSelect = '';
    for($i=0;$i<$digits;$i++){
        $randomChar = $passwordString[rand(0, strlen($passwordString)-1)];
        $randomSelect = $randomSelect.$randomChar ;
        $passwordString = str_replace($randomChar,"",$passwordString);

    }
    return $randomSelect;

}

you should reuse the chars in $passwordString

Upvotes: 0

Niet the Dark Absol
Niet the Dark Absol

Reputation: 324650

Firstly, you shouldn't reject $digits being higher than the number of characters to choose from. You could easily receive GeneratePassword(10,'A'), in which case you'd need to return AAAAAAAAAA.

Second, you shouldn't remove selected characters from the string. The examples even include duplicate characters (2c00acb for instance).

Apart from that, your code seems to work. I would suggest, though, that you calculate strlen($passwordString) up front and save it in a variable, rather than computing it once for every iteration of the loop.

Upvotes: 4

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