Build small, reusable functions. Every function should have types and a clear name. Try each task first, then compare with the solution.
Exercise 1: tax and discount
Write addTax(float $price, float $rate = 18): float and applyDiscount(float $price, float $percent): float. Use both to calculate: 1000, 10% off, then 18% tax.
Show a possible solution
<?php
function addTax(float $price, float $rate = 18): float
{
return $price * (1 + $rate / 100);
}
function applyDiscount(float $price, float $percent): float
{
return $price * (1 - $percent / 100);
}
$final = addTax(applyDiscount(1000, 10));
echo $final;1062Exercise 2: average
Write average(float ...$numbers): float that returns the average of any number of values. If no values are given, return 0.
Show a possible solution
<?php
function average(float ...$numbers): float
{
if ($numbers === []) {
return 0;
}
return array_sum($numbers) / count($numbers);
}
echo average(70, 80, 90) . "\n";
echo average();80
0Exercise 3: a grade function
Write gradeFor(int $score): string that returns A for 90+, B for 75+, C for 60+ and F otherwise. Use match (true).
Show a possible solution
<?php
function gradeFor(int $score): string
{
return match (true) {
$score >= 90 => "A",
$score >= 75 => "B",
$score >= 60 => "C",
default => "F",
};
}
echo gradeFor(82) . gradeFor(40);BFExercise 4: a formatter with a callback
Write formatAll(array $items, callable $formatter): array that applies the formatter to every item. Use it to wrap every word in <li> tags.
Show a possible solution
<?php
function formatAll(array $items, callable $formatter): array
{
return array_map($formatter, $items);
}
$list = formatAll(["Tea", "Coffee"], fn($item) => "<li>$item</li>");
echo implode("", $list);<li>Tea</li><li>Coffee</li>Exercise 5: a counter with a closure
Write makeCounter(int $start = 0): callable that returns a function. Each call to that function returns the next number.
Show a possible solution
<?php
function makeCounter(int $start = 0): callable
{
return function () use (&$start): int {
return ++$start;
};
}
$next = makeCounter(10);
echo $next() . " " . $next() . " " . $next();11 12 13