PHP if else & if else if

In PHP, the if, else, and else if statements are used to execute different blocks of code based on certain conditions. Here's a breakdown of how each of these control structures works, along with examples.

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:

$age = 20;

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

Output:

You are an adult.

if...else Statement

The if...else statement executes one block of code if a condition is true, and another block of code if it 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:

$age = 16;

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

Output:

You are not an adult.

if...else if...else Statement

The if...else if...else statement allows you to check multiple conditions, executing different blocks of code based on which condition is true.

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:

$score = 75;

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

Output:

Grade: C

Nested if Statements

You can also nest if statements within each other to create more complex conditions.

Example:

$age = 20;
$is_student = true;

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

Output:

You are an adult student.

Summary

• if: Executes a block of code if the condition is true.
• else: Executes a block of code if the if condition is false.
• else if: Checks another condition if the previous if or else if condition is false.
• Nested if: Allows more complex conditions by placing if statements inside other if statements.

These control structures are fundamental for making decisions in your PHP code based on various conditions.