PHP: if...else...elseif, and switch Tutorial

The if statement

The if statement is used to execute a block of code only if a specified condition is true. Here is the basic syntax:

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

Example:

$age = 18;

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

The if...else Statement

The if...else statement is used to execute a block of code if the condition is true, and another block of code if the condition is false. Here is the basic syntax:

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

Example:

$age = 17;
if ($age >= 18) {
    echo "You are eligible to vote.";
} else {
    echo "You are not eligible to vote yet.";
}

The if...elseif...else statement

The if...elseif...else statement is used to execute different blocks of code for different conditions. Here is the basic syntax:

if (condition1) {
    // code to be executed if condition1 is true
} elseif (condition2) {
    // code to be executed if condition2 is true and condition1 is false
} else {
    // code to be executed if all conditions are false
}

Example:

$age = 20;
if ($age < 13) {
    echo "You are a child.";
} elseif ($age >= 13 && $age < 18) {
    echo "You are a teenager.";
} else {
    echo "You are an adult.";
}

The switch statement:

The switch statement is used to perform different actions based on different conditions. It is often used as an alternative to if...elseif...else statements. Here is the basic syntax:

switch (n) {
    case label1:
        // code to be executed if n = label1
        break;
    case label2:
        // code to be executed if n = label2
        break;
    default:
        // code to be executed if n is different from all labels
}

Example:

$day = "Monday";
switch ($day) {
    case "Monday":
        echo "Today is Monday.";
        break;
    case "Tuesday":
        echo "Today is Tuesday.";
        break;
    default:
        echo "It's another day of the week.";
}