Why does this loop execute only once?

Question

I found such php code :

$a = 5;
$i  = 4;
for($i = &$a; $i < 10; ++$i);

echo "a=$a, i=$i";

I would expect this loop to be executed 4 times since $i becomes a reference to a$(right?). However loop is executed only once and outputs :

a=10, i=10

I can't figure outh why it works like this. Any ideas?

Answer 1

It works because the for statement is being processed like a single line statement as a result of the semicolon.

for($i = &$a; $i < 10; ++$i);

can also be seen as

for($i = &$a; $i < 10; ++$i) echo $i;

Without the curly brackets, the following line will be considered part of the for statement, your line being just a semicolon to indicate the end of the line.

The proper code would look like this.

$a = 5;
for($i = $a; $i < 10; ++$i) echo "a=$a, i=$i";