Control flow
if/else, the three loops, foreach's copy semantics, break and continue with levels, and why `match` beats `switch`.
Branching
<?php
$score = 72;
if ($score >= 90) {
echo "A\n";
} elseif ($score >= 70) {
echo "B\n";
} else {
echo "C\n";
}
echo $score >= 70 ? "pass\n" : "fail\n";elseif and else if are the same thing in brace syntax. In the alternative (template) syntax only elseif is allowed — else if is a parse error there.
<?php $user = ['admin' => true]; ?> <?php if ($user['admin']): ?> Welcome, admin. <?php elseif (isset($user['name'])): ?> Welcome back. <?php else: ?> Please sign in. <?php endif; ?>
while and do…while
<?php
$n = 3;
while ($n > 0) {
echo $n--, ' ';
}
echo "\n";
$tries = 0;
do {
$tries++; // the body always runs at least once
} while ($tries < 3);
echo "$tries tries\n";for
All three clauses are optional, and each may hold several comma-separated expressions.
<?php
for ($i = 0; $i < 5; $i++) {
echo $i;
}
echo "\n";
for ($lo = 0, $hi = 5; $lo < $hi; $lo++, $hi--) {
echo "$lo-$hi ";
}
echo "\n";
$i = 0;
for (;;) { // an infinite loop; break gets you out
if (++$i > 3) break;
echo $i;
}
echo "\n";⚠️ The condition is re-evaluated every iteration. for ($i = 0; $i < count($big); $i++) calls count() on every pass. Hoist it: for ($i = 0, $n = count($big); $i < $n; $i++).
foreach
The loop for arrays and objects, and the one you will use most.
<?php
$ages = ['Ada' => 36, 'Grace' => 85];
foreach ($ages as $age) {
echo $age, ' ';
}
echo "\n";
foreach ($ages as $name => $age) {
echo "$name is $age\n";
}
foreach ([[1, 'one'], [2, 'two']] as [$n, $word]) {
echo "$n=$word ";
}
echo "\n";<?php
$a = [1, 2, 3];
foreach ($a as $v) {
$a[] = $v * 10; // does not extend the loop
if (count($a) > 20) break;
}
echo count($a), " elements, loop ran 3 times\n";break and continue take a level
A plain break leaves the innermost loop. break 2 leaves two levels — which saves the flag variable that nested loops otherwise need.
<?php
$grid = [[1, 2], [3, 4], [5, 6]];
foreach ($grid as $row) {
foreach ($row as $cell) {
if ($cell === 4) {
echo "found 4, leaving both loops\n";
break 2;
}
echo $cell, ' ';
}
}
echo "\n";
for ($i = 1; $i <= 6; $i++) {
if ($i % 2 === 0) continue;
echo $i, ' ';
}
echo "\n";⚠️ continue inside a switch behaves like break — the switch counts as a loop level. If you mean "next iteration of the loop around this switch", write continue 2. PHP 7.3+ warns about the ambiguous case.
switch
switch compares with loose ==, and cases fall through unless you break.
<?php
$code = '2'; // a STRING
switch ($code) {
case 1:
echo "one\n";
break;
case 2: // matches: '2' == 2 is true
case 3:
echo "two or three\n"; // deliberate fall-through
break;
default:
echo "something else\n";
}match — what switch should have been
match is an expression, compares with ===, does not fall through, and throws if nothing matches.
<?php
$code = 2;
$label = match ($code) {
1 => 'one',
2, 3 => 'two or three',
default => 'other',
};
echo $label, "\n";
$n = 73;
echo match (true) {
$n >= 90 => "A\n",
$n >= 70 => "B\n",
default => "C\n",
};
try {
echo match ('2') { 1 => 'int one', 2 => 'int two' };
} catch (\UnhandledMatchError $e) {
echo 'UnhandledMatchError: ', $e->getMessage(), "\n";
}switch | match | |
|---|---|---|
| Compares with | == | === |
| Is an | statement | expression |
| Falls through | yes, without break | never |
| No match | silently does nothing | throws UnhandledMatchError |
| Body | statements | a single expression |
💡 Tip: match (true) with boolean arms replaces a chain of if/elseif when every branch produces a value. It reads as a table, and the compiler guarantees exactly one arm is taken.
goto
PHP has it. It can only jump forward, and only within the same file and function — never into a loop.
<?php
for ($i = 0; $i < 10; $i++) {
if ($i === 3) goto done;
}
done:
echo "jumped out at $i\n";In practice break 2 covers everything goto is good for. Mention it so you recognise it; do not reach for it.
Reference: Control Structures in the PHP Manual.