PHP Data Types

Last modified on: October 19, 2024

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<h3>PHP Data Types</h3>
<p>PHP has several built-in data types, which can be categorized into scalar types and compound types:</p>
<h3>Scalar Types</h3>
<ol>
<li><strong>Integer</strong>: Whole numbers, positive or negative (e.g., <code>42</code>, <code>-5</code>).</li>
<li><strong>Float</strong> (or double): Numbers with a decimal point (e.g., <code>3.14</code>, <code>-0.001</code>).</li>
<li><strong>String</strong>: A sequence of characters, enclosed in single or double quotes (e.g., <code>'Hello'</code>, <code>"World"</code>).</li>
<li><strong>Boolean</strong>: Represents two possible values: <code>true</code> or <code>false</code>.</li>
</ol>
<h3>Compound Types</h3>
<ol>
<li><strong>Array</strong>: A collection of values, which can be of different types. Arrays can be indexed or associative (e.g., <code>$array = [1, 2, 3]</code> or <code>$assocArray = ['key' =&gt; 'value']</code>).</li>
<li><strong>Object</strong>: An instance of a class that can contain properties and methods (e.g., <code>$obj = new ClassName();</code>).</li>
<li><strong>Callable</strong>: A type that can refer to a function or a method that can be called.</li>
</ol>
<h3>Special Types</h3>
<ol>
<li><strong>NULL</strong>: Represents a variable with no value or a non-existent object (e.g., <code>$var = null;</code>).</li>
</ol>
<h3>Type Casting</h3>
<p>PHP supports type casting, allowing you to convert between types, like:</p>
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<pre class="language-php"><code>$int = 10;
$float = (float)$int; // Cast integer to float
$string = (string)$int; // Cast integer to string</code></pre>
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<h3>Type Checking</h3>
<p>You can check the type of a variable using functions like <code>gettype()</code>, <code>is_int()</code>, <code>is_float()</code>, etc.</p>
<h4>1. <strong>Integer</strong></h4>
<p>An integer is a whole number without any decimal points.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$age = 30; // Integer
echo $age; // Output: 30</code></pre>
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<h4>2. <strong>Float</strong></h4>
<p>A float is a number that has a decimal point.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$price = 19.99; // Float
echo $price; // Output: 19.99</code></pre>
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<h4>3. <strong>String</strong></h4>
<p>A string is a sequence of characters, which can include letters, numbers, and symbols.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$greeting = "Hello, World!"; // String
echo $greeting; // Output: Hello, World!</code></pre>
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<h4>4. <strong>Boolean</strong></h4>
<p>A boolean represents a truth value: either <code>true</code> or <code>false</code>.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$isStudent = true; // Boolean
if ($isStudent) {
    echo "You are a student."; // Output: You are a student.
}</code></pre>
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<h4>5. <strong>Array</strong></h4>
<p>An array can hold multiple values in a single variable. It can be indexed or associative.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$fruits = array("Apple", "Banana", "Cherry"); // Indexed array
echo $fruits[1]; // Output: Banana

$person = array("name" =&gt; "John", "age" =&gt; 25); // Associative array
echo $person["name"]; // Output: John</code></pre>
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<h4>6. <strong>Object</strong></h4>
<p>An object is an instance of a class that can contain properties and methods.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>class Car {
    public $color;
    public function setColor($color) {
        $this-&gt;color = $color;
    }
}

$myCar = new Car();
$myCar-&gt;setColor("Red");
echo $myCar-&gt;color; // Output: Red</code></pre>
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<h4>7. <strong>NULL</strong></h4>
<p>NULL represents a variable with no value.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$var = null; // NULL
if (is_null($var)) {
    echo "Variable is null."; // Output: Variable is null.
}</code></pre>
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<h3>Type Casting</h3>
<p>You can convert one data type to another.</p>
<p><strong>Example:</strong></p>
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<pre class="language-php"><code>$number = "42"; // String
$intNumber = (int)$number; // Cast to integer
echo $intNumber; // Output: 42</code></pre>
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