Shuffle array in PHP
PHP shuffle function shuffle array in PHP. The article uses this function to build a minimalistic console-based game, “The Quiz Game”.
Introduction
PHP arrays are flexible in terms of the elements datatypes. Arrays can have mixed types, including objects. The element’s index denotes its position in an array, where the leftmost element has an index of zero. One cool thing is random shuffling in an array. Randomized shuffling is super important if you’re trying to develop a game of chance, for instance, Poker.
This article includes an array of objects. These objects are instances of a class Quiz. The class represents a typical quiz question with multiple answers. This article demonstrates how to shuffle array in PHP and builds a console-based program that displays random quiz questions. So let’s start without further ado.
The Quiz Class
Here’s the “Quiz” class. The array will hold the instances of this class.
class Quiz {
private $questionText;
private $answersArray;
function __construct($questionText, $answersArray) {
$this->questionText = $questionText;
$this->answersArray = $answersArray;
}
function getQuestion() {
return $this->questionText;
}
function getAnswersArray() {
return $this->getAnswersArray;
}
function setQuestion($questionText) {
$this->questionText = $questionText;
}
function setAnswersArray($answersArray) {
$this->answersArray = $answersArray;
}
}
The Quiz Objects
Here are a few instances of the “Quiz” class.
$question1 = new Quiz("What is the capital of USA?",
[
["Washington, D.C", "Correct"],
["California", "Incorrect"],
["Texas", "Incorrect"]
]);
$question2 = new Quiz("Where is the Great Wall located?",
[
["Canada", "Incorrect"],
["China", "Correct"],
["India", "Incorrect"]
]);
$question3 = new Quiz("Who was the first man on the moon?",
[
["Joseph Swan", "Incorrect"],
["Nicola Tesla", "Incorrect"],
["Neil Armstrong", "Correct"]
]);
Every object is initialized with a text-based question and an array having nested arrays, each with an answer and the status, “Correct” or “Incorrect”.
The Quiz Game – Shuffle array in PHP
The envisioned quiz game needs to pick randomly from an array of “Quiz” objects. Fortunately, PHP features a function shuffle(). So, let’s see how that works.
PHP shuffle
shuffle(array &$array): bool
The shuffle function in PHP takes an array by reference, shuffling the elements in place. Let’s see an example.
$arr = ["First", "Second", "Third", "Fourth", "Fifth"];
print_r($arr);
/*
OUTPUT BEFORE SHUFFLING
Array
(
[0] => First
[1] => Second
[2] => Third
[3] => Fourth
[4] => Fifth
)
*/
Here’s the output after shuffling.
shuffle($arr);
print_r($arr);
/*
OUTPUT AFTER SHUFFLING
Array
(
[0] => Fourth
[1] => Third
[2] => First
[3] => Fifth
[4] => Second
)
*/
Voila! That’s how to shuffle array in PHP.
The Quiz Game – Shuffle array in PHP
Now that we know how to shuffle array in PHP let’s build “The Quiz Game”.
Helper functions
The game needs some functions for core functionalities. Let’s check these out.
function randomize(&$quizArray) {
//If array is exhausted return null.
if(empty($quizArray)) return null;
//Select a random index.
$randomIndex = rand(0, count($quizArray) - 1);
//Shuffle array.
shuffle($quizArray);
//Pick the question at random index.
$question = array_splice($quizArray, $randomIndex, 1);
return $question[0];
}
The randomize() function picks questions at random and passes them on to the central control.
function displayQuestion($questionCount,$question) {
echo 'Quesion#'.$questionCount.': '.$question->getQuestion().PHP_EOL;
echo 'Option1. '.$question->getAnswersArray()[0][0].PHP_EOL;
echo 'Option2. '.$question->getAnswersArray()[1][0].PHP_EOL;
echo 'Option3. '.$question->getAnswersArray()[2][0].PHP_EOL;
}
As the name implies, the function displayQuestion() has logic for displaying question and answer choices.
function verifyAnswer($question, $answer) {
if(!in_array($answer, [1, 2, 3, -1])) {
throw new Exception('Input not supported');
}
if($answer == "-1") {
return -1;
}
foreach($question->getAnswersArray() as $k => $v) {
//If the user picks the right answer.
if(($answer - 1)== intval($k) && $v[1] == "Correct") {
return 1;
}
}
return 0;
}
The verifyAnswer() function checks the user input and reacts accordingly.
Main Code
Here’s the main code or entry point of “The Quiz Game”.
//Array of Quiz Objects
$quizQuestions = [$question1, $question2, $question3];
echo "Welcome to the Quiz Game".PHP_EOL.PHP_EOL;
$name = readline("Please enter your name: ");
$score = 0;
$questionCount = 1;
echo "Rules\n10 Points for a correct answer\n0 Points for an incorrect answer".PHP_EOL.PHP_EOL;
$question = randomize($quizQuestions);
while(isset($question)) {
displayQuestion($questionCount + 1, $question);
$answer = readline("Enter 1, 2, 3. Press -1 to quit: ");
$status = verifyAnswer($question,$answer);
//If the answer is correct
if($status == 1) {
$score += 10;
$questionCount++;
}
elseif($status == 0) {
$score -=5;
$questionCount++;
}
elseif($status == -1) {
break;
}
$question = randomize($quizQuestions);
}
//Show Result
echo PHP_EOL.'SUMMARY';
echo $name.' attempted '.$questionCount.' questions'.PHP_EOL;
echo $name.' scored '.$score.' out of '.$questionCount*10;
Output
Here are snippets of a run, starting from the intro and the first question.
Then we have more questions.
Finally, here’s the summary.
Voila! I scored 30 out of 30. After all, I knew the answers beforehand 🙂 Now, that’s a minimalistic console-based game that uses array shuffling in PHP. There’s still alot of room for improvement, of course. However, the objective here was to demonstrate a scenario where shuffling is useful.
Conclusion
The article shows how to shuffle array in PHP. It includes information about the PHP shuffle function and its usage. The article uses array shuffling in “The Quiz Game”, a minimalistic console-based game. The array shuffling is vital in similar scenarios, for instance, modelling a Poker game or probabilistic models. Hopefully, you’ve enjoyed the article and also the super simple “Quiz Game”. Stay tuned for more at FuelingPHP.
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