简单的PHP for循环错误

Question

Just started learning. Here's what I have:

<?php 
$i = 0;
$num = $i * 12;

for ($i=0; $i<13; $i++) {

echo($i." times 12 = ".$num."<br>");
}

?>

The outcome should be:

1 times 12 = 12

2 times 12 = 24

3 times 12 = 36

etc...

The outcome I actually get is:

1 times 12 = 0

2 times 12 = 0

3 times 12 = 0

any ideas?

Answer 1

It is because you have this declaration before for loop:

$i = 0; $num = $i * 12;

so always $num will be 0. Just place it into for:

for ($i=1; $i<13; $i++) {
   $num = $i*12;
   echo($i." times 12 = ".$num."<br>");
}

You don't need declare $i variable before for loop. This variable will be overwritten. There is simple test:

$i = 5;
for($i = 1; $i<10; $i++);

echo $i;

OUTPUT:

10