What are Variables? Static Variables & Switch Statement in PHP

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A. Variables in PHP

Variables are named containers used to store data values in a program. In PHP, all variables start with the $ sign followed by the variable name.

Rules for PHP Variables:

• A variable starts with $ followed by the name (e.g., $name)
• Variable name must begin with a letter or underscore (_)
• Variable name cannot start with a number
• Variable names are case-sensitive ($age and $Age are different)
• PHP is a loosely typed language — no need to declare data type explicitly

Example:

<?php
  $name = "John";   // String variable
  $age = 25;        // Integer variable
  $price = 99.5;    // Float variable
?>

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B. Static Variables

A static variable is a local variable that retains its value between function calls instead of being destroyed when the function ends.

• Defined using the keyword static before the variable name
• It is initialized only once (during the first function call)
• On subsequent calls, it remembers its previous value
• Useful for counters and tracking state across function calls

Syntax:

static $variable_name = value;

Example:

<?php
  function counter() {
      static $count = 0;
      $count++;
      echo "Count = $count <br>";
  }

  counter();  // Output: Count = 1
  counter();  // Output: Count = 2
  counter();  // Output: Count = 3
?>

Here, $count is not reset to 0 on each call because it is declared as static.

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C. PHP Program to Illustrate Switch Statement

The switch statement is used to perform different actions based on different conditions. It is an alternative to multiple if...elseif...else statements.

Syntax:

switch (expression) {
    case value1:
        // code block
        break;
    case value2:
        // code block
        break;
    default:
        // code block
}

Program:

<?php
  $day = 3;

  switch ($day) {
      case 1:
          echo "Monday";
          break;
      case 2:
          echo "Tuesday";
          break;
      case 3:
          echo "Wednesday";
          break;
      case 4:
          echo "Thursday";
          break;
      case 5:
          echo "Friday";
          break;
      case 6:
          echo "Saturday";
          break;
      case 7:
          echo "Sunday";
          break;
      default:
          echo "Invalid day number";
  }
?>

Output:

Wednesday

Key Points about Switch:

• The break keyword stops execution and exits the switch block
• Without break, execution falls through to the next case
• The default case executes when no matching case is found
• Switch compares the expression with each case using loose comparison (==)

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Conclusion: Variables are fundamental building blocks in PHP for storing data. Static variables provide persistence across function calls, and the switch statement offers a clean and readable way to handle multiple conditional branches.