Loops
Looping
Sometimes we need to repeat a task over and over again.
<?php
$friends = array("Caroline",
"Max", "Earl", "Oleg", "Han");
echo $friends[0] . ", ";
echo $friends[1] . ", ";
echo $friends[2] . ", ";
echo $friends[3] . ", ";
echo $friends[4];
?>//Output Below
Caroline, Max, Earl, Oleg, Han
Look at all these lines of code! Might a loop be more readable without repeating ourselves?
While loops
A so-called while loop runs a block of code as long as a certain condition is true.
<?php
$number = 1;
while ($number < 4) {
$number += 1;
echo $number . ", ";
}
?>//Output Below
2, 3, 4,
Yes! This while loop increases $number by 1 as long as it's less than 4. Once at 4, the condition turns false and the loop stops.
Do while loops
A do while loop is a type of while loop that first runs the block of code then checks if the condition is true.
<?php
$number = 1;
do {
$number += 1;
echo $number;
} while ($number > 4);
?>//Output Below
2
See that? No matter what the condition, the loop runs at least once.
Psst: notice that the do while loop ends with a semicolon.
For loops
The for loop is a very popular type of loop. It has 3 parts: the value, the condition, and a way to change the value.
<?php
for ($i = 0; $i < 4; $i++) {
echo $i . ", ";
}
?>//Output Below
0, 1, 2, 3, 4,
Sweet! $i starts at 0 and increases as long as the condition is true. Once it returns false, the loop stops.
Psst: $i++ is an even shorter version of $i += 1.
Foreach loop
Now, the so-called foreach loop works only on arrays, because it goes through each of their elements.
<?php
$heroes = array("Batman", "Robin", "Batgirl");
foreach ($heroes as $hero) {
echo $hero . ", ";
}
?>//Output Below
Batman, Robin, Batgirl,
Nice! In every so-called iteration, the value of an element is stored in $hero.
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