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PHP Conditions

PHP Conditions – Complete Guide with Examples

Welcome to phponline.in, your go-to platform for mastering PHP from scratch.
In this chapter, we will cover PHP conditional statements — the foundation of decision-making in programming.

Without conditions, PHP code would only run in a straight line. But in real-world applications (like login systems, shopping carts, payment gateways, and form validations), we need to make decisions dynamically.

That’s where PHP conditions come in.

You will Learn

  1. Introduction to PHP Conditions

  2. Why Are Conditions Important in PHP?

  3. Types of Conditional Statements in PHP

  4. PHP if Statement

  5. PHP if...else Statement

  6. PHP if...elseif...else Statement

  7. PHP Nested if Statements

  8. PHP switch Statement

  9. PHP Alternative Syntax for Conditions

  10. Using Conditions with Logical Operators (&&, ||, !)

  11. Comparison Operators in Conditions

  12. Ternary Operator (?:) in PHP

  13. Null Coalescing Operator (??)

  14. Combining Conditions with Arrays & Loops

  15. Real-World Applications of PHP Conditions

  16. Common Mistakes in Using Conditions

  17. Best Practices for Writing PHP Conditions

  18. PHP Conditions in Object-Oriented Programming (OOP)

  19. PHP Conditions in Web Applications

  20. Performance Considerations for Conditions

1. Introduction to PHP Conditions

Conditions allow PHP scripts to make decisions during execution.
For example:

$age = 20;
if ($age >= 18) {
echo "You are eligible to vote.";
}

Here, PHP checks the condition $age >= 18. If true, it executes the block.

2. Why Are Conditions Important in PHP?

  • Form validations (checking empty fields, email formats)

  • User authentication (login success/failure)

  • E-commerce (discounts, stock availability)

  • Error handling

  • Role-based permissions

3. Types of Conditional Statements in PHP

  1. if statement

  2. if...else

  3. if...elseif...else

  4. Nested if

  5. switch statement

  6. Ternary operator

  7. Null coalescing operator

4. PHP if Statement

Syntax:

if (condition) {
// code to execute if condition is true
}

Example:

$score = 90;
if ($score >= 80) {
echo "Excellent performance!";
}

5. PHP if...else Statement

$password = "12345";
if ($password == "admin123") {
echo "Access Granted";
} else {
echo "Access Denied";
}

6. PHP if...elseif...else Statement

$marks = 65;
if ($marks >= 80) {
echo "Grade A";
} elseif ($marks >= 60) {
echo "Grade B";
} else {
echo "Grade C";
}

7. PHP Nested if Statements

$user = "admin";
$loggedIn = true;if ($loggedIn) {
if ($user == “admin”) {
echo “Welcome Admin!”;
}
}

8. PHP switch Statement

$day = "Monday";
switch ($day) {
case "Monday":
echo "Start of the week!";
break;
case "Friday":
echo "Weekend is near!";
break;
default:
echo "Just another day.";
}

9. PHP Alternative Syntax for Conditions

Useful in templates (e.g., HTML + PHP mix).

<?php if ($age >= 18): ?>
<p>You can vote.</p>
<?php else: ?>
<p>You cannot vote.</p>
<?php endif; ?>

10. Using Conditions with Logical Operators

  • && (AND)

  • || (OR)

  • ! (NOT)

$loggedIn = true;
$isAdmin = false;if ($loggedIn && $isAdmin) {
echo “Welcome Admin!”;
}

11. Comparison Operators in Conditions

Operator Description Example
== Equal $a == $b
=== Identical $a === $b
!= Not equal $a != $b
> Greater than $a > $b
< Less than $a < $b

12. Ternary Operator in PHP

$age = 20;
echo ($age >= 18) ? "Adult" : "Minor";

13. Null Coalescing Operator (??)

$username = $_GET['user'] ?? "Guest";
echo $username;

14. Combining Conditions with Arrays & Loops

$users = ["Alice", "Bob", "Charlie"];
foreach ($users as $user) {
if ($user == "Bob") {
echo "Found Bob!";
}
}

15. Real-World Applications of PHP Conditions

  • Login authentication

  • Payment success/failure response

  • E-commerce discount systems

  • Content personalization

  • Error handling in APIs

16. Common Mistakes in Using Conditions

  • Using = instead of ==

  • Forgetting break in switch

  • Over-nesting conditions

17. Best Practices for Writing PHP Conditions

  • Keep conditions simple

  • Use strict comparison (===) where possible

  • Avoid deeply nested conditions

18. PHP Conditions in OOP

In classes, conditions are widely used for validation.

class User {
public $role;
public function checkAccess() {
if ($this->role === "admin") {
return "Access granted";
}
return "Access denied";
}
}

19. PHP Conditions in Web Applications

  • Login systems

  • Form validation

  • Content management systems (CMS)

  • E-commerce websites

20. Performance Considerations

  • Place most likely conditions first

  • Use switch for multiple fixed values

  • Avoid unnecessary evaluations

PHP conditions, PHP if else, PHP switch case, PHP conditional operators, PHP decision making, PHP programming basics, PHP control structures

Related Topics

 Frequently Asked Questions (FAQ)

Q1: What is the difference between if and switch in PHP?
A: if is better for complex conditions, while switch is ideal for checking one variable against multiple fixed values.

Q2: Is elseif the same as else if?
A: Yes, both work the same, but elseif is the recommended syntax.

Q3: Can I nest multiple conditions in PHP?
A: Yes, PHP supports nested if and switch statements.

Q4: Which operator is best for checking null values?
A: Use the null coalescing operator (??) for best performance and readability.

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