Static properties and methods in PHP - Step-by-Step Execution

Concept Flow - Static properties and methods

Class Definition

↓

Define static property

↓

Define static method

↓

Access static property/method

↓

Use without creating object

↓

Static property/method used directly

↓

End

Shows how static properties and methods are defined in a class and accessed directly without creating an object.

Execution Sample

PHP

<?php
class Counter {
  public static $count = 0;
  public static function increment() {
    self::$count++;
  }
}
Counter::increment();
echo Counter::$count;
?>

This code defines a class with a static property and method, increments the static count, and prints it.

Execution Table

Step	Action	Static Property Value	Output
1	Class Counter defined with static property count=0	0
2	Call Counter::increment()	1
3	Echo Counter::$count	1	1
4	End of script	1

💡 Script ends after printing static property value 1

Variable Tracker

Variable	Start	After Step 2	Final
Counter::$count	0	1	1

Key Moments - 2 Insights

Why can we access Counter::$count without creating an object?

Because $count is a static property, it belongs to the class itself, not to any object instance. See execution_table step 3.

Why do we use self::$count inside the static method?

Inside the class, self:: refers to the class itself, so self::$count accesses the static property. See execution_table step 2.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of Counter::$count after step 2?

A 1

B 0

C 2

D Undefined

💡 Hint

Check the 'Static Property Value' column at step 2 in the execution_table.

At which step is the static method increment() called?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Action' column in the execution_table for the method call.

If we remove 'static' from the property declaration, what happens when accessing Counter::$count?

A It works the same

B It causes an error

C It prints 0 always

D It prints null

💡 Hint

Static properties must be declared static to be accessed with :: syntax, see variable_tracker and execution_table.

Concept Snapshot

Static properties and methods belong to the class, not objects.
Use 'static' keyword to declare them.
Access with ClassName::$property or ClassName::method().
Inside class, use self::$property or self::method().
No need to create an object to use static members.

Full Transcript

This example shows how to define and use static properties and methods in PHP. The class Counter has a static property $count initialized to 0. The static method increment() increases $count by 1 using self::$count++. We call Counter::increment() without creating an object. Then we print Counter::$count which outputs 1. Static members belong to the class itself, so they can be accessed directly using the class name and :: operator. Inside the class, self:: is used to refer to static members. This allows shared data or behavior across all uses of the class without needing instances.