Understanding PHP Conditional Statements: if, else, and switch Explained

Today, we will explore PHP conditional statements, which allow you to execute different blocks of code based on certain conditions. Conditional statements are fundamental in programming as they enable decision-making in your code. Let's dive into the various conditional statements available in PHP.

Types of PHP Conditional Statements

1. if Statement

2. if...else Statement

3. if...elseif...else Statement

4. switch Statement

1. if Statement

The if statement executes a block of code if a specified condition is true.

Syntax:

if (condition) {
    // Code to be executed if the condition is true
}

Example:

<?php
    $age = 20; // Assign the value 20 to the variable $age

    if ($age >= 18) { // Check if $age is greater than or equal to 18
        echo "You are an adult."; // If the condition is true, output "You are an adult."
    }
    // Outputs: You are an adult.
?>

2. if...else Statement

The if...else statement executes one block of code if a condition is true and another block of code if the condition is false.

Syntax:

if (condition) {
    // Code to be executed if the condition is true
} else {
    // Code to be executed if the condition is false
}

Example:

<?php
    $age = 16; // Assign the value 16 to the variable $age

    if ($age >= 18) { // Check if $age is greater than or equal to 18
        // $age >= 18 i.e. 16 >= 18 is false
        echo "You are an adult."; // This line will not be executed since the condition is false
    } else {
        // If condition is false, the else block will run
        echo "You are a minor."; // This line will be executed
    }
    // Outputs: You are a minor.
?>

3. if...elseif...else Statement

The if...elseif...else statement allows you to test multiple conditions. If one of the conditions is true, the corresponding block of code is executed.

Syntax:

if (condition1) {
    // Code to be executed if condition1 is true
} elseif (condition2) {
    // Code to be executed if condition2 is true
} else {
    // Code to be executed if neither condition1 nor condition2 is true
}

Example:

<?php
    $score = 85; // Assign the value 85 to the variable $score

    if ($score >= 90) {
        // $score >= 90 i.e. 85 >= 90 is false
        echo "Grade: A"; // This line will not be executed since the condition is false
    } elseif ($score >= 80) {
        // $score >= 80 i.e. 85 >= 80 is true
        echo "Grade: B"; // This line will be executed since the condition is true
    } elseif ($score >= 70) {
        // $score >= 70 i.e. 85 >= 70 is true but the previous condition was met, so this block is not executed
        echo "Grade: C";
    } else {
        // If all conditions are false, the else block will run
        echo "Grade: F";
    }
    // Outputs: Grade: B
?>

4. switch Statement

The switch statement is used to perform different actions based on different conditions. It is a more efficient way to compare a single variable against multiple values.

Syntax:

switch (n) {
    case label1:
        // Code to be executed if n == label1
        break;
    case label2:
        // Code to be executed if n == label2
        break;
    // You can have any number of case statements
    default:
        // Code to be executed if n doesn't match any case
}

Example:

<?php
    $day = "Tuesday"; // Assign the value "Tuesday" to the variable $day

    switch ($day) { // Start switch statement to check the value of $day
        case "Monday": // Check if $day is "Monday"
            echo "Today is Monday."; // This line will not be executed since $day is not "Monday"
            break; // Exit switch statement
        case "Tuesday": // Check if $day is "Tuesday"
            echo "Today is Tuesday."; // This line will be executed since $day is "Tuesday"
            break; // Exit switch statement
        case "Wednesday": // Check if $day is "Wednesday"
            echo "Today is Wednesday."; // This line will not be executed since $day is not "Wednesday"
            break; // Exit switch statement
        default: // Default case if none of the above cases match
            echo "Unknown day."; // This line will not be executed since one of the cases matched
    }
    // Outputs: Today is Tuesday.
?>

Best Practices for Conditional Statements

1. Use Braces for All Control Structures:

   • Always use braces {} for if, else, and elseif blocks, even for single-line statements. This improves readability and prevents errors.

    if ($condition) {
        // Do something
    }

2. Keep Conditions Simple:

   • Break down complex conditions into smaller, understandable parts.

    <?php
        $isAdult = $age >= 18; // Assign true to $isAdult if $age is greater than or equal to 18, otherwise false
        $hasPermission = $isAdmin || $isAdult; // Assign true to $hasPermission if $isAdmin or $isAdult is true

        if ($hasPermission) {
            // Do something if $hasPermission is true
        }
    ?>

3. Avoid Deep Nesting:

   • Refactor deeply nested code into functions to improve readability and maintainability.

   • Note: The topic of functions will be covered in upcoming blogs.

    <?php
        function processOrder($order) {
            if ($order->isValid()) { // Check if the order is valid
                if ($order->isPaid()) { // Check if the order is paid
                    // Process the order if it is valid and paid
                }
            }
        }
    ?>

4. Useswitchfor Multiple Conditions on a Single Variable:

   • When comparing a single variable against multiple values, use a switch statement for better readability and efficiency.

    switch ($status) {
        case "active":
            // Code for active status
            break;
        case "inactive":
            // Code for inactive status
            break;
        default:
            // Code for unknown status
    }

Conclusion

Today, we explored PHP conditional statements, including if, if...else, if...elseif...else, and switch statements. Conditional statements are crucial for making decisions in your code based on different conditions.