Solved

8 Unique Numbers

Posted on 2008-06-23
7
206 Views
Last Modified: 2008-07-01
Hello,

I need to randomly generate 8 UNIQUE random numbers.

No number may be used more than once.

So this number is good:
    53962471

This number is NOT because some numbers are duplicated:
    11223344


What is the shortest/simplest way to do this?
0
Comment
Question by:hankknight
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7 Comments
 
LVL 24

Expert Comment

by:glcummins
ID: 21846706
Not sure that this method is the simplest, but it will definitely work and is extensible in case your requirements change:


<?php
 
$uniqueNumbers = 8;
$highestValue = 9;
$lowestValue = 1;
 
$arrGeneratedNumbers = array();
 
for ($i = 0; $i<$uniqueNumbers; $i++)
{
	$foundUnique = false;
	
	while (!$foundUnique)
	{
		$newNumber = rand($lowestValue, $highestValue);
		if (!in_array($newNumber, $arrGeneratedNumbers))
		{
			$arrGeneratedNumbers[] = $newNumber;
			$foundUnique = true;
		}
	}
}
 
foreach ($arrGeneratedNumbers as $number)
{
	echo $number;
}
 
?>

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0
 
LVL 24

Assisted Solution

by:glcummins
glcummins earned 300 total points
ID: 21846735
Here is a simpler method, but it limits you to the eight numbers that you enter into the array:
<?php
 
$arrNumbers = array(1,2,3,4,5,6,7,8);
 
shuffle($arrNumbers);
 
foreach ($arrNumbers as $number)
{
	echo $number;
}
 
?>

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0
 
LVL 14

Assisted Solution

by:agriesser
agriesser earned 100 total points
ID: 21846818
Try this.
<?php
 
$magicnumbers = array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);
$randomnumber = '';
 
for($i = 0; $i < 8; $i++)
{
  $r = rand(0, 9 - $i);
  $randomnumber .= $magicnumbers[$r];
  unset($magicnumbers[$r]);
  $magicnumbers = array_values($magicnumbers);
}
 
echo $randomnumber;
 
?>

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LVL 11

Assisted Solution

by:spoxox
spoxox earned 100 total points
ID: 21846981
Is there a requirement for the length of the random numbers? Assuming NO
Are all digits 0-9 eligible? Assuming YES
Is zero acceptable? Assuming YES
<?php
$uNums = array();
$digits = array(1,2,3,4,5,6,7,8,9,0);
$req = 8;
$nCount = 0; 
while ($nCount < $req) {
  shuffle($digits); // randomly shuffle array of digits
  $nLen = rand(1,10);  // determine length of next random digit string
  $num = ""; // initialize digit string
  for ($i = 0; $i < $nLen; $i++) { // collect $nLen unique digits
    $num = $num.$digits[$i];
  }
  if (!in_array($num, $uNums)) { // verify digit string/number is not in array
    $uNums[] = $num; // add digit string/number to array
    $nCount++;
  }
}
?>

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0
 
LVL 16

Author Comment

by:hankknight
ID: 21847104
I feel silly answering my own question but the ideas keep getting more complex.

One of your ideas triggered a lightening bolt in my head and I came up with this.

What do you think?
<?php
 $str = '0123456789';
 $shuffled = str_shuffle($str);
 echo substr($shuffled,-8);
?>

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0
 
LVL 24

Expert Comment

by:glcummins
ID: 21847129
Yes, that will work, and will allow you to start with as large a data set as desired.
0
 
LVL 16

Accepted Solution

by:
hankknight earned 0 total points
ID: 21847132
Or even better:
<?php
echo substr(str_shuffle('0123456789'),-8);
?>

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