随机数组

Question

How would I randomize this Array so that when I use a foreach loop it would it would switch index 0 with key 1 and to randomize the order?

I have tried $variable= array_rand($variable,count($variable)) but it prints out

  0 => int 0
  1 => int 1
  2 => int 2
  3 => int 3
  4 => int 4

Here is my code:

foreach ($variable as $key)

    array (size=10)
          0 => 
            object(stdClass)[25]
              public 'id' => string '24' (length=2)
              public 'course_name' => string 'Office Automation' (length=17)
              public 'test_name' => string 'Test 2' (length=6)
              public 'total_questions' => string '10' (length=2)
              public 'duration' => string '20' (length=2)
              public 'total_marks' => string '20' (length=2)
              public 'question' => string 'Question1' (length=9)
              public 'option1' => string 'ans1' (length=4)
              public 'option2' => string 'ans2' (length=4)
              public 'option3' => string 'ans3' (length=4)
              public 'option4' => string 'ans4' (length=4)
              public 'ans' => string 'D' (length=1)
              public 'count' => string '1' (length=1)
          1 => 
            object(stdClass)[26]
              public 'id' => string '25' (length=2)
              public 'course_name' => string 'Office Automation' (length=17)
              public 'test_name' => string 'Test 2' (length=6)
              public 'total_questions' => string '10' (length=2)
              public 'duration' => string '20' (length=2)
              public 'total_marks' => string '20' (length=2)
              public 'question' => string 'Question2' (length=9)
              public 'option1' => string 'ans1' (length=4)
              public 'option2' => string 'ans2' (length=4)
              public 'option3' => string 'ans3' (length=4)
              public 'option4' => string 'ans4' (length=4)
              public 'ans' => string 'A' (length=1)
              public 'count' => string '2' (length=1)
          2 => 
            object(stdClass)[27]
              public 'id' => string '26' (length=2)
              public 'course_name' => string 'Office Automation' (length=17)
              public 'test_name' => string 'Test 2' (length=6)
              public 'total_questions' => string '10' (length=2)
              public 'duration' => string '20' (length=2)
              public 'total_marks' => string '20' (length=2)
              public 'question' => string 'Question3' (length=9)
              public 'option1' => string 'ans1' (length=4)
              public 'option2' => string 'ans2' (length=4)
              public 'option3' => string 'ans3' (length=4)
              public 'option4' => string 'ans4' (length=4)
              public 'ans' => string 'B' (length=1)
              public 'count' => string '3' (length=1)

I need to randomize the order so that when it prints it will print a new order everytime.

The array stores question and question option in the keys/indexes

Answer 1

If all you are looking to achieve is to shuffle the values of an array without any need to keep them associated with their original keys, you might want to consider looking at the shuffle() function.

This function takes an array by reference (note the argument &$array in the docs for this function) so it will shuffle the array you pass in and return a boolean relating to its success.

As an example:

// Setup an array filled with values:
$myArray = array("banana", "orange", "elephant", "toadstool");

print_r($myArray); //Returns: Array ( [0] => banana [1] => orange [2] => elephant [3] => toadstool )

At this stage, the array is in the order that we initialised it in. If we use shuffle() and give it $myArray as the argument, we will end up with a different order:

shuffle($myArray);

print_r($myArray); //Might print: Array ( [0] => elephant [1] => toadstool [2] => banana [3] => orange )

If you ran shuffle again you would get a potentially different order. (Why ' potentially '?! Well, because it may randomly select the same order again especially if the array is small like this example one).

It is worth noting that:

[Shuffle] uses a pseudo random number generator that is not suitable for cryptographic purposes.

Source: Shuffle Docs

---

Considerations:

If you didn't want to change the order of your array you could use something like array_rand() which would return you random keys from your array which you could then look up. It's the same idea except the array is never changed.

Assuming the array above:

$randomKey = array_rand($myArray); //Random key is now 2

echo "My random array value is: ".$myArray[$randomKey]; //Prints: My random array value is: orange

---

As the manual tells us:

This function assigns new keys to the elements in array. It will remove any existing keys that may have been assigned, rather than just reordering the keys.

How does this affect me? Well if you had specific keys like this:

$myArray = array(
    "firstFruit" => "banana", 
    "anotherFruit" => "orange", 
    "animal" => "elephant", 
    "plant"=>"toadstool"
);

After your first call to shuffle() your array would look like this:

Array ( 
    [0] => orange 
    [1] => toadstool 
    [2] => banana 
    [3] => elephant 
)

and your associated keys are lost!