A for
loop is commonly used to execute a code block a specific number of times.
for (#expression 1; #expression 2; #expression 3) { # code block }
The for
loop syntax includes 3 expressions:
- The first is evaluated only one time before the first iteration.
- The second is evaluated before each iteration. If it is
TRUE
, the code block is executed. Otherwise, the loop terminates. - The third is evaluated after each iteration. Note that expressions 1 and 2 have semicolons after them.
In our counting to 10 example, the syntax becomes:
for ($count = 1; $count < 11; $count++) { echo "The count is: " . $count . "\n"; }
The first expression is $count = 1
, this initializes the $count
variable to 1
.
At each iteration, the second expression ($count < 11
) is evaluated. As long as this is TRUE
, the code block executes.
The final expression ($count++
) executes after every iteration. In this example, $count
is being incremented by 1
each iteration.
After 10 iterations, the value of the $count
variable is 11
. This makes the second expression FALSE
and the loop execution terminates.
Instructions
We’re going to use a for
loop to make a countdown. Our goal is to make it count from 10
down to 3
and then say "Ready!"
, "Set!"
, "Go!"
.
Begin by making a for loop that prints the loop variable at each iteration:
- Use
$i
for your loop variable. - Initialize
$i
to10
. - Continue looping while
$i
is greater than or equal to zero. - Decrement
$i
on each iteration. - Print
$i
on each iteration followed by a newline.
Use if
, elseif
and else
statements to modify the output slightly:
- When the loop variable
$i
is10
and until its value is down to3
, it should simply print the loop variable followed by a newline. - When the loop variable is
2
, it should print"Ready!"
, followed by a newline. - When the loop variable is
1
, it should print"Set!"
, followed by a newline. - When the loop variable is
0
, it should print"Go!"
.