Solved

8 Unique Numbers

Posted on 2008-06-23
7
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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
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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Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

 
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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