PHP If Statement Tutorial

1. Basic Syntax

The syntax of an if statement is as follows:

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

Here's a simple example:

<?php
$age = 18;

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

In this example, the message "You are an adult." will be displayed because the condition is true.

2. If-Else Statement

You can extend the if statement with an else block to execute alternative code if the condition is false:

<?php
$age = 16;

if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are not an adult.";
}
?>

In this case, "You are not an adult." will be displayed because the condition is false.

3. If-Else If-Else Statement

For multiple conditions, you can use the else if clause:

<?php
$score = 75;

if ($score >= 90) {
    echo "Grade: A";
} elseif ($score >= 80) {
    echo "Grade: B";
} elseif ($score >= 70) {
    echo "Grade: C";
} else {
    echo "Grade: D";
}
?>

This code checks the value of $score and prints the corresponding grade.

4. Nested If Statements

You can also nest if statements inside each other:

<?php
$age = 20;
$hasID = true;

if ($age >= 18) {
    if ($hasID) {
        echo "You can enter the club.";
    } else {
        echo "You need an ID to enter the club.";
    }
} else {
    echo "You are not old enough to enter the club.";
}
?>

In this case, the inner if checks if the user has an ID if they are old enough.

5. Using Logical Operators

You can combine multiple conditions using logical operators like and (&&), or (||), and not (!):

<?php
$age = 25;
$hasTicket = true;

if ($age >= 18 && $hasTicket) {
    echo "You can enter the concert.";
} else {
    echo "You cannot enter the concert.";
}
?>

In this example, the user must be both 18 or older and have a ticket to enter the concert.

6. Ternary Operator

PHP also offers a shorthand version of the if-else statement using the ternary operator:

<?php
$age = 17;
$message = ($age >= 18) ? "You are an adult." : "You are not an adult.";
echo $message;
?>

This code evaluates the condition and assigns the appropriate message based on the result.

7. Summary

The if statement is a powerful tool for controlling the flow of your PHP programs. By using if, else, and elseif, you can make decisions in your code based on different conditions. Always ensure your conditions are correctly defined to avoid unexpected behaviors.