When to use `if`, `switch`, and `match` in PHP

• The if Statement
  • Syntax of if Statement
  • Example
  • When to Use if
• The switch Statement
  • Syntax of switch Statement
  • Example
  • When to Use switch
• The match Expression
  • Syntax of match Expression
  • Example
  • When to Use match
• Practical Scenarios
• Scenario 1: User Authentication
• Scenario 2: Processing Form Input
• Scenario 3: HTTP Status Codes
• Choosing the Right Tool
• Additional Resources

One of the fundamental aspects of any programming language is its ability to control the flow of the program based on different conditions. PHP offers several ways to accomplish this, with if, switch, and match statements being the most prominent. In this article, we'll delve into each of these conditional statements, exploring their syntax, use cases, and the scenarios in which each should be used.

Conditional statements allow developers to execute different blocks of code based on specific conditions. This ability is crucial for making decisions within a program, handling different input values, and managing various states in an application.

¶The if Statement

The if statement is the most basic and widely used conditional statement in PHP. It evaluates a condition and executes a block of code if the condition is true.

¶Syntax of if Statement

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

¶Example

$age = 20;

if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are a minor.";
}

¶When to Use if

• Simple Conditions: Use if for straightforward, single-condition checks.
• Multiple Conditions: Combine if with else if and else for more complex decision-making.
• Boolean Checks: Ideal for checking true/false values.

¶The switch Statement

The switch statement is an alternative to the if statement, often used when dealing with multiple possible values for a single variable. It compares the variable against different cases and executes the corresponding block of code.

¶Syntax of switch Statement

switch (variable) {
    case value1:
        // Code to be executed if variable == value1
        break;
    case value2:
        // Code to be executed if variable == value2
        break;
    default:
        // Code to be executed if variable doesn't match any case
}

¶Example

$day = "Tuesday";

switch ($day) {
    case "Monday":
        echo "Start of the work week!";
        break;
    case "Tuesday":
        echo "Second day of the work week!";
        break;
    case "Friday":
        echo "Last workday of the week!";
        break;
    default:
        echo "It's the weekend!";
}

¶When to Use switch

• Multiple Known Values: Ideal when a variable can have one of several known values.
• Clean Code: Provides a cleaner and more readable alternative to multiple if-else statements.
• Exact Matches: Best suited for exact value matches rather than range or boolean checks.

¶The match Expression

Introduced in PHP 8.0, the match expression is a more powerful and flexible version of the switch statement. It returns a value based on the condition that matches.

¶Syntax of match Expression

$result = match (variable) {
    value1 => result1,
    value2 => result2,
    default => defaultResult,
};

¶Example

$status = 404;

$message = match ($status) {
    200 => "OK",
    404 => "Not Found",
    500 => "Internal Server Error",
    default => "Unknown status code",
};

echo $message; // Outputs: Not Found

¶When to Use match

• Return Values: Use match when you need to return values based on conditions.
• Type Safety: Ensures strict type comparisons, avoiding potential pitfalls of loose comparisons in switch.
• Conciseness: Offers a more concise and expressive syntax for mapping conditions to results.

¶Practical Scenarios

To understand when to use if, switch, and match, let's look at some practical scenarios:

¶Scenario 1: User Authentication

When validating user credentials, an if statement is appropriate because you are dealing with boolean checks.

$username = "admin";
$password = "password123";

if ($username === "admin" && $password === "password123") {
    echo "Welcome, admin!";
} else {
    echo "Invalid credentials.";
}

¶Scenario 2: Processing Form Input

When processing a form where a single input can have multiple known values, a switch statement is ideal.

$action = $_POST['action'];

switch ($action) {
    case 'save':
        saveData();
        break;
    case 'delete':
        deleteData();
        break;
    case 'update':
        updateData();
        break;
    default:
        echo "Invalid action.";
}

¶Scenario 3: HTTP Status Codes

When mapping HTTP status codes to messages, the match expression is the most suitable due to its concise syntax and return value capabilities.

$statusCode = getStatusCodeFromServer();

$message = match ($statusCode) {
    200 => "OK",
    301 => "Moved Permanently",
    404 => "Not Found",
    500 => "Internal Server Error",
    default => "Unknown status code",
};

echo $message;

¶Choosing the Right Tool

Choosing between if, switch, and match depends on the specific requirements of your code:

• Use if for simple, boolean-based conditions and complex, multi-conditional checks.
• Use switch for scenarios with multiple known values for a single variable, where readability and maintainability are crucial.
• Use match for more concise and type-safe condition-result mappings, particularly when returning values directly.

By understanding the strengths and appropriate use cases for each conditional statement, you can write more efficient, readable, and maintainable PHP code.

¶Additional Resources

• PHP if statement documentation
• PHP switch statement documentation
• PHP match expression documentation

By leveraging these conditional statements appropriately, you can ensure your PHP applications are robust and adaptable to varying conditions.