PHP Conditional Statements: if, switch, and match

Branching Rules

A conditional chooses which code should run for the current state. Good branches make business rules visible and keep invalid input away from the main path.

Use if for ranges or combined conditions, match for one value mapped to one result, and guard clauses to stop early when a requirement fails.

if and elseif

Conditions are checked from top to bottom.
Only the first matching branch in one chain runs.
Put the most specific overlapping rule before a broader rule.

Delivery Band

<?php
$orderTotal = 850;

if ($orderTotal >= 1000) {
    $delivery = 'Free';
} elseif ($orderTotal >= 500) {
    $delivery = 'Reduced';
} else {
    $delivery = 'Standard';
}

echo $delivery;

Output

Reduced

Guard Clauses

A guard clause handles an invalid or exceptional case first, then returns or throws. This keeps the successful path less deeply nested.

Require a Positive Quantity

<?php
function lineTotal(float $price, int $quantity): float
{
    if ($quantity < 1) {
        throw new InvalidArgumentException('Quantity must be positive.');
    }

    return $price * $quantity;
}

echo lineTotal(99.5, 2);

Output

switch and match

switch is a statement and needs break to prevent fall-through in ordinary cases. match is an expression, compares strictly, returns a value, and does not fall through.

A match without a matching arm throws UnhandledMatchError unless a default arm exists.

Map a Status with match

<?php
$status = 'paid';
$label = match ($status) {
    'pending' => 'Awaiting payment',
    'paid' => 'Ready to ship',
    'cancelled' => 'Closed',
    default => 'Unknown status',
};

echo $label;

Output

Ready to ship

Condition Traps

PHP converts values to Boolean in a condition. The values false, 0, 0.0, an empty string, the string "0", an empty array, and null are falsey. A non-empty string such as "false" is truthy, so validate external text instead of relying on its appearance.

switch compares case values loosely, while match uses strict identity. That difference matters when form and query values arrive as strings: the integer 0 and string "0" may enter the same switch case but different match arms.

Decision Shape	Use	Reason
Ranges or combined predicates	if / elseif	Each branch can express a different condition.
Several statements with intentional fall-through	switch	Case flow can be shared when documented.
One input mapped to one value	match	Strict comparison, no fall-through, and a returned value.
Invalid prerequisite	guard clause	Stops the rejected path before main work.

Use === when 0, false, null, or an empty string has a distinct meaning.
Calculate an expensive value once instead of repeating the call in several branches.
Extract long nested decisions into named functions or guard clauses.
Use parentheses to reveal the intended grouping of && and ||.

Choose the Branch Form

0 of 2 checked

Q1. Which construct strictly maps one input value to one returned result?

match while include

Q2. Why use a guard clause?

To increase nesting To stop invalid cases early To convert PHP to HTML

Branching Defects

Assignment inside a condition
Use comparison deliberately and enable static analysis for accidental assignment.
Broad rule placed first
Order overlapping ranges from most specific to most general.
Missing switch break
Add break unless fall-through is intentional and documented.
No match default
Cover every enum case or handle the possible UnhandledMatchError.

Try this next

Model a Decision

0 of 2 completed

Test decision boundaries
Implement a tiered discount with guard clauses and verify negative, zero, threshold-minus-one, threshold, and above-threshold inputs. Order overlapping conditions from invalid and specific cases toward the broad default.
Map a request method
Use match to return Read for GET, Write for POST, and Unsupported by default. Keep the default arm explicit for methods outside the supported set.

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PHP Conditional Statements: if, switch, and match

Branching Rules

if and elseif

Delivery Band

Guard Clauses

Require a Positive Quantity

switch and match

Map a Status with match

Condition Traps

Choose the Branch Form

Q1. Which construct strictly maps one input value to one returned result?

Q2. Why use a guard clause?

Branching Defects

Assignment inside a condition

Broad rule placed first

Missing switch break

No match default

Model a Decision

Test decision boundaries

Map a request method

Repeat and Reuse Logic

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