Introduction to Data Types in PHP
PHP is a loosely typed language, meaning variables do not have a fixed data type. PHP automatically determines the type of a variable based on its assigned value. However, PHP also provides mechanisms for explicit type conversion when needed.
1. Data Types in PHP
PHP supports eight primary data types, divided into three categories:
1.1 Scalar (Single Value) Data Types
These types store a single value at a time.
| Data Type | Description | Example |
| Integer | Whole numbers (positive or negative) | 10, -50, 1000 |
| Float (Double) | Decimal numbers | 3.14, -0.99, 10.5E3 |
| String | Sequence of characters | “Hello, PHP!”, ‘123’ |
| Boolean | Represents true or false | true, false |
1.2 Compound (Multiple Values) Data Types
These types can store multiple values at once.
| Data Type | Description | Example |
| Array | Stores multiple values in a single variable | [“Apple”, “Banana”, “Cherry”] |
| Object | Represents an instance of a class | $obj = new Car(); |
1.3 Special Data Types
These types are used in specific scenarios.
| Data Type | Description | Example |
| NULL | Represents a variable with no value | $var = NULL; |
| Resource | Holds external resources like database connections | $file = fopen(“file.txt”, “r”); |
2. Type Checking in PHP
PHP provides functions to check a variable’s type.
Example: Checking Data Types
<?php
$var1 = 10;
$var2 = 3.14;
$var3 = “Hello”;
$var4 = true;
echo gettype($var1); // Output: integer
echo gettype($var2); // Output: double (float)
echo gettype($var3); // Output: string
echo gettype($var4); // Output: boolean
?>
PHP Functions for Type Checking
| Function | Description | Example |
| is_int() | Checks if a variable is an integer | is_int(100) → true |
| is_float() | Checks if a variable is a float | is_float(3.14) → true |
| is_string() | Checks if a variable is a string | is_string(“Hello”) → true |
| is_bool() | Checks if a variable is a boolean | is_bool(true) → true |
| is_null() | Checks if a variable is NULL | is_null(NULL) → true |
| is_array() | Checks if a variable is an array | is_array([1,2,3]) → true |
| is_object() | Checks if a variable is an object | is_object(new Car()) → true |
3. Type Conversion in PHP
PHP allows automatic (implicit) type conversion and manual (explicit) type conversion.
3.1 Implicit Type Conversion (Type Juggling)
PHP automatically converts data types when necessary.
Example: Implicit Type Conversion
<?php
$x = “10” + 5; // “10” (string) is converted to an integer
echo $x; // Output: 15
?>
- Here, PHP converts “10” (string) into 10 (integer) before performing the addition.
More Examples of Implicit Conversion
<?php
$y = “5.5” * 2; // “5.5” (string) becomes 5.5 (float)
echo $y; // Output: 11.0
$z = true + 1; // true (1) + 1 = 2
echo $z; // Output: 2
?>
3.2 Explicit Type Conversion (Type Casting)
When needed, you can manually convert a variable’s type using type casting or conversion functions.
Type Casting in PHP
You can convert a variable to a different type by prefixing it with the desired type in parentheses.
<?php
$var = “100”;
$int_var = (int)$var; // Convert string to integer
echo $int_var; // Output: 100
?>
Available Type Casts:
| Cast Syntax | Converts To |
| (int) $var or (integer) $var | Integer |
| (float) $var or (double) $var or (real) $var | Float |
| (bool) $var or (boolean) $var | Boolean |
| (string) $var | String |
| (array) $var | Array |
| (object) $var | Object |
| (unset) $var | NULL |
3.3 Type Conversion Using Functions
PHP provides functions for explicit type conversion.
| Function | Description | Example |
| intval() | Converts a value to an integer | intval(“123”) → 123 |
| floatval() | Converts a value to a float | floatval(“3.14”) → 3.14 |
| strval() | Converts a value to a string | strval(100) → “100” |
Example: Conversion Functions
<?php
$num = “123.45”;
$int_num = intval($num); // Convert to integer
$float_num = floatval($num); // Convert to float
$string_num = strval($num); // Convert to string
echo $int_num; // Output: 123
echo $float_num; // Output: 123.45
echo $string_num; // Output: “123.45”
?>
4. Automatic Type Conversion in Expressions
PHP dynamically converts types in expressions depending on the operation.
Example 1: String to Integer Conversion
<?php
$result = “50” + 20; // “50” is converted to an integer
echo $result; // Output: 70
?>
Example 2: Boolean to Integer Conversion
<?php
$bool = true + 5; // true is converted to 1
echo $bool; // Output: 6
?>
5. Converting Arrays and Objects
PHP allows conversion between arrays and objects using casting and type functions.
Converting an Array to an Object
<?php
$array = [“name” => “John”, “age” => 30];
$object = (object)$array;
echo $object->name; // Output: John
?>
Converting an Object to an Array
<?php
class Person {
public $name = “John”;
public $age = 30;
}
$person = new Person();
$array = (array)$person;
print_r($array);
// Output: Array ( [name] => John [age] => 30 )
?>
6. Summary of PHP Type Conversion
- PHP automatically converts types when needed (Implicit Type Conversion).
- Developers can manually convert types using type casting or conversion functions.
- PHP allows dynamic type conversion in expressions for flexible coding.
Conclusion
Understanding data types and type conversion in PHP is crucial for handling variables, performing calculations, and ensuring data integrity. Using type checking, type casting, and conversion functions, developers can write efficient and error-free code.