Static Properties and Methods
In object-oriented PHP, you can define both static properties and static methods inside a class. These are different from regular (instance) properties and methods, and understanding their difference is key to writing effective PHP code.
Static properties and static methods belong to the class itself, not to any specific object created from that class. This means you access them using the class name, instead of using an object. In contrast, instance properties and instance methods are tied to individual objects, and each object has its own copy of these.
Key differences
- Static properties are shared by all objects of a class; instance properties are unique to each object;
- Static methods can be called without creating an object; instance methods require an object to be called;
- Static properties and methods use the
statickeyword in their declaration.
Typical use cases
- Use static properties to store information that should be shared across all instances, such as a counter tracking the number of objects created;
- Use static methods for utility functions that do not depend on object data, such as simple calculations or factory methods that create objects.
Understanding when to use static versus instance members helps you organize your code, avoid unnecessary objects, and clarify how data is shared in your application.
Code Example
Below, you will see a Counter class that demonstrates how to use static properties and methods, which belong to the class itself rather than to individual objects.
static_example.php
12345678910111213141516171819202122<?php // Define a class with static property and static method class Counter { // Static property to hold the count value public static $count = 0; // Static method to increment the count public static function increment() { self::$count++; } } // Access and display static property without creating an object // Initial value echo "Initial count: " . Counter::$count . "\n"; // Call static method to increment the count Counter::increment(); Counter::increment(); // Display updated static property echo "Count after incrementing twice: " . Counter::$count . "\n";
The Counter class has a static property $count that belongs to the class itself rather than to any individual object. The static method increment() modifies this property using self::$count.
Because the property and method are static, we can access them directly through the class name Counter::$count and Counter::increment() without creating an object. Each call to increment() increases the shared count, and the updated value is reflected when we access $count again.
Static members are useful when you need a value or behavior that is shared across all instances of a class or when no instance is needed at all.
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In object-oriented PHP, you can define both static properties and static methods inside a class. These are different from regular (instance) properties and methods, and understanding their difference is key to writing effective PHP code.
Static properties and static methods belong to the class itself, not to any specific object created from that class. This means you access them using the class name, instead of using an object. In contrast, instance properties and instance methods are tied to individual objects, and each object has its own copy of these.
Key differences
- Static properties are shared by all objects of a class; instance properties are unique to each object;
- Static methods can be called without creating an object; instance methods require an object to be called;
- Static properties and methods use the
statickeyword in their declaration.
Typical use cases
- Use static properties to store information that should be shared across all instances, such as a counter tracking the number of objects created;
- Use static methods for utility functions that do not depend on object data, such as simple calculations or factory methods that create objects.
Understanding when to use static versus instance members helps you organize your code, avoid unnecessary objects, and clarify how data is shared in your application.
Code Example
Below, you will see a Counter class that demonstrates how to use static properties and methods, which belong to the class itself rather than to individual objects.
static_example.php
12345678910111213141516171819202122<?php // Define a class with static property and static method class Counter { // Static property to hold the count value public static $count = 0; // Static method to increment the count public static function increment() { self::$count++; } } // Access and display static property without creating an object // Initial value echo "Initial count: " . Counter::$count . "\n"; // Call static method to increment the count Counter::increment(); Counter::increment(); // Display updated static property echo "Count after incrementing twice: " . Counter::$count . "\n";
The Counter class has a static property $count that belongs to the class itself rather than to any individual object. The static method increment() modifies this property using self::$count.
Because the property and method are static, we can access them directly through the class name Counter::$count and Counter::increment() without creating an object. Each call to increment() increases the shared count, and the updated value is reflected when we access $count again.
Static members are useful when you need a value or behavior that is shared across all instances of a class or when no instance is needed at all.
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