PHP Array to String Conversion (favourite colours chosen by user)

Description: Write a PHP exercise for array to string conversion.

Rules and hints:

• Create a form that accepts a name and some colors (checkboxes).
• After the submit, the data goes to another page.
• Show the user name and the selected colors as a list.
• The name and at least one color are required.

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Step 1: the form (index.html)

<form action="data.php" method="post">
    Name: <input type="text" name="username" required><br><br>

    Select your favourite colors:<br>
    <input type="checkbox" name="colors[]" value="Red"> Red
    <input type="checkbox" name="colors[]" value="Green"> Green
    <input type="checkbox" name="colors[]" value="Blue"> Blue
    <input type="checkbox" name="colors[]" value="Yellow"> Yellow<br><br>

    <button type="submit">Send</button>
</form>

The name colors[] (with the square brackets) tells PHP to collect all the selected values in an array.

Step 2: data.php

<?php
$username = trim($_POST["username"] ?? "");
$colors = $_POST["colors"] ?? [];

if ($username === "" || empty($colors)) {
    exit("Name and at least one color are required.");
}

echo "Hello " . htmlspecialchars($username) . "<br>";
echo "Your favourite colors: " . htmlspecialchars(implode(", ", $colors));
?>

Output:

How it works

• $_POST["colors"] is an array of the checked boxes.
• implode(", ", $colors) converts the array to a text. See how to convert an array to a string.
• htmlspecialchars() protects the page from XSS.

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PHP Array to String Conversion (favourite colours chosen by user)

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