software-development-company-logo

Tag: Lesson 5: Control Structures

  • Lesson 5: Control Structures

    Section 1: Introduction to PHP
    Section 2: PHP Fundamentals
    Section 3: Working with Forms and User Input
    Section 4: Object-Oriented PHP
    Section 5: PHP and Databases
    Section 6: Advanced PHP Concepts
    Section 7: Real-World Projects
    Section 8: PHP Best Practices

    Control structures in PHP enable developers to implement decision-making and repetitive tasks. This lesson covers conditional statements (if-else, switch-case) and loops (for, while, do-while, foreach) in detail, with examples and use cases.

    5.1 If-Else Statements

    What is an If-Else Statement?

    • If-else statements execute a block of code based on a condition.
    • Syntax:
      • <?php
      if (condition) {
      // Code to execute if condition is true
      } elseif (another_condition) {
      // Code to execute if another_condition is true
      } else {
      // Code to execute if no condition is true
      }
      ?>

    Example: Simple If-Else

    <?php
    = 18) {
    echo “You are eligible to vote.”;
    } else {
    echo “You are not eligible to vote.”;
    }
    ?>
    ?>

    Example: If-Elseif-Else

    <?php
    = 90) {
    echo “Grade: A”;
    } elseif ($score >= 75) {
    echo “Grade: B”;
    } else {
    echo “Grade: C”;
    }
    ?>
    ?>

    5.2 Switch-Case Statements

    What is a Switch-Case Statement?

    • A switch-case statement evaluates a variable against multiple possible values and executes corresponding code.
    • Syntax:
      • <?php
      switch (variable) {
      case value1:
      // Code to execute if variable equals value1
      break;
      case value2:
      // Code to execute if variable equals value2
      break;
      default:
      // Code to execute if no case matches
      }
      ?>

    Example: Switch-Case

    <?php

    ?>

    5.3 Loops

    Why Use Loops?

    Loops allow repetitive execution of code blocks as long as a specified condition is met.

    5.3.1 For Loop

    Syntax

    <?php
    for (initialization; condition; increment/decrement) {
    // Code to execute
    }
    ?>

    Example: Print Numbers

    <?php
    “;
    }
    ?>
    ?>

    Example: Multiplication Table

    <?php
    “;
    }
    ?>
    ?>

    5.3.2 While Loop

    Syntax

    <?php
    while (condition) {
    // Code to execute
    }
    ?>

    Example: Print Even Numbers

    <?php
    “;
    $num += 2;
    }
    ?>
    ?>

    Example: Factorial Calculation

    <?php
    0) {
    $factorial *= $n;
    $n–;
    }

    echo “Factorial: $factorial”;
    ?>
    ?>

    5.3.3 Do-While Loop

    Syntax

    <?php
    do {
    // Code to execute
    } while (condition);
    ?>

    Example: Print Numbers

    <?php
    “;
    $num++;
    } while ($num <= 5); ?>
    ?>

    Difference Between While and Do-While

    • In a while loop, the condition is checked before the first iteration.
    • In a do-while loop, the code executes at least once, even if the condition is false.

    5.3.4 Foreach Loop

    Purpose

    • Designed specifically for iterating over arrays.

    Syntax

    <?php
    foreach ($array as $value) {
    // Code to execute
    }
    ?>

    Example: Iterate Over Array

    <?php
    “;
    }
    ?>
    ?>

    Example: Key-Value Pairs

    <?php
    “Alice”, “Age” => 25, “City” => “New York”);

    foreach ($person as $key => $value) {
    echo “$key: $value
    “;
    }
    ?>
    ?>

    Activities and Exercises

    1. If-Else Statement:
      • Write a script to determine whether a given year is a leap year or not.
    2. Switch-Case Statement:
      • Create a script that takes a number (1–7) and outputs the corresponding day of the week.
    3. Loops:
      • Use a for loop to print the first 10 Fibonacci numbers.
      • Write a while loop that prints all odd numbers between 1 and 20.
      • Use a foreach loop to display all items in an associative array of student names and grades.

    Assignment

    Create a PHP script that:

    1. Uses an if-else statement to check whether a number is positive, negative, or zero.
    2. Uses a switch-case statement to output the month name when given a number (1–12).
    3. Uses a for loop to calculate the sum of numbers from 1 to 100.
    4. Uses a while loop to find the largest power of 2 less than a given number.
    5. Uses a foreach loop to display a list of products with their prices.

    Summary

    Control structures are crucial in PHP for decision-making and iteration. The concepts covered in this lesson form the backbone of logical programming in PHP and will be extensively used in real-world applications. Let me know if you’d like additional examples or exercises!