If - Else

Part of the Fundamentals section of Coddy's PHP journey — lesson 29 of 71.

Sometimes you need your code to do one thing when a condition is true, and something different when it's false. The else clause lets you handle both cases.

Add else after your if block to specify what happens when the condition is false:

<?php
$age = 15;

if ($age >= 18) {
    echo "You can vote";
} else {
    echo "You cannot vote yet";
}
?>

Since $age is 15, the condition is false, so PHP runs the else block and prints "You cannot vote yet".

For more than two possibilities, chain conditions using elseif:

<?php
$score = 75;

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

PHP checks each condition from top to bottom and runs the first block that matches. Once a match is found, it skips all remaining conditions. Here, 75 fails the first two checks but passes $score >= 70, so "Grade: C" is printed.

Challenge

Easy

Read two integers from input: a temperature and a hour (in 24-hour format, 0-23).

Determine the appropriate message based on the following conditions:

If the temperature is below 0, print Freezing conditions
Otherwise, if the temperature is below 15, print Cold weather
Otherwise, if the temperature is below 25, print Pleasant weather
Otherwise, print Hot weather

Then, on a new line, print a greeting based on the hour:

If the hour is less than 12, print Good morning!
Otherwise, if the hour is less than 18, print Good afternoon!
Otherwise, print Good evening!

Example:

If the inputs are 20 and 9, the output should be:

Pleasant weather
Good morning!

If the inputs are -5 and 14, the output should be:

Freezing conditions
Good afternoon!

Cheat sheet

The else clause specifies what happens when an if condition is false:

<?php
$age = 15;

if ($age >= 18) {
    echo "You can vote";
} else {
    echo "You cannot vote yet";
}
?>

Use elseif to chain multiple conditions:

<?php
$score = 75;

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

PHP checks conditions from top to bottom and executes the first matching block, then skips the rest.

Try it yourself

<?php
// Read input
$temperature = intval(fgets(STDIN));
$hour = intval(fgets(STDIN));

// TODO: Write your code below
// Determine the weather message based on temperature

// Determine the greeting based on hour

?>

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

If - Else

Cheat sheet

All lessons in Fundamentals