Star Patterns and Basic Logic Questions in PHP

Welcome to a special blog post where we delve into some interesting PHP challenges: star patterns and basic logic questions. These exercises are great for honing your programming skills and understanding loops, and conditionals in PHP.

Star Patterns

Star patterns are a common exercise in programming that help you understand nested loops. Here are some examples:

1. Right-Angled Triangle:

    <?php
        $n = 5; // Number of rows
        for ($i = 1; $i <= $n; $i++) {
            for ($j = 1; $j <= $i; $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Outputs:
        // *
        // * *
        // * * *
        // * * * *
        // * * * * *
    ?>
   

2. Inverted Right-Angled Triangle:

    <?php
        $n = 5;
        for ($i = $n; $i >= 1; $i--) {
            for ($j = 1; $j <= $i; $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Outputs:
        // * * * * *
        // * * * *
        // * * *
        // * *
        // *
    ?>
   

3. Left-Angled Triangle:

    <?php
        $n = 5;
        for ($i = 1; $i <= $n; $i++) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= $i; $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Output:
        //         *
        //       * *
        //     * * *
        //   * * * *
        // * * * * *
    ?>
   

4. Inverted Left-Angled Triangle:

    <?php
        $n = 5;
        for ($i = $n; $i >= 1; $i--) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= $i; $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Output:
        // * * * * *
        //   * * * *
        //     * * *
        //       * *
        //         *
    ?>
   

5. Pyramid:

    <?php
        $n = 5;
        for ($i = 1; $i <= $n; $i++) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;"; // Two spaces
            }
            for ($j = 1; $j <= (2 * $i - 1); $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Outputs:
        //         *
        //       * * *
        //     * * * * *
        //   * * * * * * *
        // * * * * * * * * *
    ?>
   

6. Diamond:

    <?php
        $n = 5;
        for ($i = 1; $i <= $n; $i++) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= (2 * $i - 1); $j++) {
                echo "* ";
            }
            echo "<br>";
        }
        for ($i = $n-1; $i >= 1; $i--) {
            for ($j = $n; $j > $i; $j--) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= (2 * $i - 1); $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Outputs:
        //         *
        //       * * *
        //     * * * * *
        //   * * * * * * *
        // * * * * * * * * *
        //   * * * * * * *
        //     * * * * *
        //       * * *
        //         *
    ?>
   

7. Sandglass Pattern:

    <?php
        $n = 5;
        // Upper part
        for ($i = $n; $i >= 1; $i--) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= (2 * $i - 1); $j++) {
                echo "* ";
            }
            echo "<br>";
        }
        // Lower part
        for ($i = 2; $i <= $n; $i++) {
            for ($j = $i; $j < $n; $j++) {
                echo "&nbsp;&nbsp;";
            }
            for ($j = 1; $j <= (2 * $i - 1); $j++) {
                echo "* ";
            }
            echo "<br>";
        }
   
        // Output:
        // * * * * * * * * *
        //   * * * * * * *
        //     * * * * *
        //       * * *
        //         *
        //       * * *
        //     * * * * *
        //   * * * * * * *
        // * * * * * * * * *
    ?>
   

Basic Logic Questions

1. Swapping of Two Variables:

<?php
    $a = 5;
    $b = 10;

    // Swapping without using a third variable
    echo "Before swapping: a = $a, b = $b<br>";
    $a = $a + $b; // a becomes 15
    $b = $a - $b; // b becomes 5 (15 - 10)
    $a = $a - $b; // a becomes 10 (15 - 5)
    echo "After swapping: a = $a, b = $b<br>";
?>

2. Find the Largest Number Among Three Numbers:

<?php
    $num1 = 10;
    $num2 = 20;
    $num3 = 30;

    if ($num1 >= $num2 && $num1 >= $num3) {
        echo "$num1 is the largest number.";
    } elseif ($num2 >= $num1 && $num2 >= $num3) {
        echo "$num2 is the largest number.";
    } else {
        echo "$num3 is the largest number.";
    }
?>

3. Check if a Number is a Leap Year or Not:

<?php
    $year = 2024;

    if (($year % 4 == 0 && $year % 100 != 0) || ($year % 400 == 0)) {
        echo "$year is a leap year.";
    } else {
        echo "$year is not a leap year.";
    }
?>

4. Write a Program to Find the Area of a Circle:

<?php
    $radius = 5;
    $area = 3.14 * ($radius * $radius);

    echo "The area of the circle with radius $radius is " . round($area, 2) . ".";
?>

Conclusion

In this blog post, we covered various star patterns and basic logic questions in PHP. These exercises help solidify your understanding of loops and conditionals, which are fundamental concepts in PHP programming. Try implementing these patterns and logic questions on your own to further enhance your coding skills.