Random String Generation?

[random1]

I'm looking for a function that creates a random string that contains random letters, numbers and symbols.

 

Also it needs to generate it in a way that there are no repeating characters.

 

Any ideas?

[Psycho]

This forum is to get help with code you have written. have you even attempted this?

[cunoodle2]

I'd try the second result here..

http://tinyurl.com/3ct9923

[voip03]

<?php

$uletter= mt_rand(65,90);// Upper case letters.
echo chr($uletter);

$uletter= mt_rand(97,122);// lower case letters.
echo chr($uletter);

$uletter= mt_rand(48,57);// Numerica numbers.
echo chr($uletter);

$uletter= mt_rand(32,47);// Symbol.
echo chr($uletter);
?>

 

http://www.ascii.cl/htmlcodes.htm

[random1]

This forum is to get help with code you have written. have you even attempted this?

 

Yeah I attempted it using mt_rand like voip03 did, but his is far more elegant. I'll get started on this now

[Psycho]

This forum is to get help with code you have written. have you even attempted this?

 

Yeah I attempted it using mt_rand like voip03 did, but his is far more elegant. I'll get started on this now

 

Well, it will get somewhat complicated (or inefficient) to use that logic while enforcing the requirement for no repeating characters. I have a fairly easy implementation in mind, but I want to at least see you make an attempt rather than just writing it for you.

[xyph]

Here's a hint - using an array and shuffle() will make things easy. array_slice() can be used to get only part of an array. range() can be used to generate a range of ASCII characters into an array.

 

That's your solution. Give an attempt to code it and we'll help further.

[random1]

I ended up using:

 

function rand_str($len, $norepeat = true)
{
$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*';
$max = strlen($chars) - 1;

if($norepeat && $len > $max + 1)
{
	throw new Exception('Non repetitive random string can\'t be longer than charset');
}

$rand_chars = array();

while($len)
{
	$picked = $chars[mt_rand(0, $max)];

	if($norepeat)
	{
		if(!array_key_exists($picked, $rand_chars))
		{
			$rand_chars[$picked] = true;
			$len--;
		}
	}
	else
	{
		$rand_chars[] = $picked;
		$len--;
	}
}

return implode('', $norepeat ? array_keys($rand_chars) : $rand_chars);   
}

echo rand_str(32, true);

 

Sample output: bkWfyRME%qYHncUF$BjgPLxei5JdSmGs

 

I'll test it more but I'm rather happy with it 

[Psycho]

OK, now that you have at least attempted it, I'll show you a more efficient method. You should avoid using loops for things when there are other methods at your disposal. That function is inefficient as it need to run a loop for each and every character - especially since it has to repeat whenever a duplicate character is encountered. That is just a waste.

 

Also, I would suggest not using variable names such as "$norepeat" - when the value is FALSE you have a double negative (by virtue of the no) which results in a true. If a variable is supposed to be true/false, name it such that it is more logical (i.e. $repeat). You can always check for a negative.

 

lastly, I would suggest making the list of characters as an additional parameter for the function. That give's you more flexibility.

 

Anyway, this will do the same thing in a much more efficient manner

function randomString($length, $charList, $repeat=false)
{
if(!$repeat && $length>strlen($charList))
{
	throw new Exception('Non repetitive random string can\'t be longer than charset');
    }
    //Create an array of the characters (add additional if needed)
    $charsAry = str_split(str_repeat($charList, ceil($length/strlen($charList))));
    //Randomize the array
    shuffle($charsAry);
    //Return the random string
    return implode(array_slice($charsAry, 0, $length));
}

$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*';
echo randomString(32, $chars);