PHP for Loop

Use a for loop when you know how many times you want to repeat something.

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<?php
for ($i = 1; $i <= 5; $i++) {
    echo $i . " ";
}

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1 2 3 4 5

The three parts

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for (start; condition; step) { ... }

1. Start ($i = 1): runs once, before the loop.
2. Condition ($i <= 5): checked before each round. The loop continues while it is true.
3. Step ($i++): runs after each round.

It is the same logic as a while loop, but with the counter handling written in one line.

Counting down

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5

<?php
for ($i = 5; $i >= 1; $i--) {
    echo $i . " ";
}
echo "Lift off!";

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5 4 3 2 1 Lift off!

Bigger steps

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<?php
for ($i = 0; $i <= 20; $i += 5) {
    echo $i . " ";
}

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0 5 10 15 20

Sum of numbers

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<?php
$sum = 0;

for ($i = 1; $i <= 10; $i++) {
    $sum += $i;
}

echo "Sum: $sum";

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Sum: 55

Looping over array positions

You can use for with an array when you need the index. Compute count() once, so PHP does not do it every round.

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<?php
$names = ["Ana", "Ben", "Cara"];

for ($i = 0, $total = count($names); $i < $total; $i++) {
    echo ($i + 1) . ". " . $names[$i] . "\n";
}

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1. Ana
2. Ben
3. Cara

If you do not need the index, foreach is simpler and safer.

Starting at 0 or 1

Array positions start at 0, so loops over arrays usually start at 0 and use < the length. Loops that count rounds for people usually start at 1 and use <=.

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<?php
for ($i = 1; $i <= 5; $i++) {
    echo "7 x $i = " . (7 * $i) . "\n";
}

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7 x 1 = 7
7 x 2 = 14
7 x 3 = 21
7 x 4 = 28
7 x 5 = 35