[RESOLVED] Interesting IF...ELSE Conundrum

LoganK

I know that you can do if...else using one line, without brackets, like this:

if ($foo == true)
     echo "True";
else
     echo "False";

My question is this: what if you needed to put another if statement after the first? If you were to do it like the previous example; i.e. this:

if ($foo == true)
     if ($bar == true)
          echo "True";
else
     echo "False";

Would this work as expected? Will PHP give a parse error? Or will it just echo true regardless of whether or not $bar is true?

thorpe

why dont you try and see?

LoganK

Don't remember where the post was, but last week around Saturday I said that my computer crashed...the hard drive broke down and although I saved my data, I had to ship it back to Toshiba and it hasn't returned yet. Now I'm using an old Win98 Sony Vaio until my main computer comes back...and you can imagine what it'd be like installing Apache, PHP, and MySQL on Win98. 😃

So I just wanna know if anyone knows what'll happen.

Drakla

Ok - that code will run fine... but is an example of the 'dangling else' - take a look at the code formatted differently

if ($foo == true)
	if ($bar == true)
		echo "True";
	else
		echo "False"; 

// exactly the same - but 'different' perceptually

if ($foo == true)
	if ($bar == true)
		echo "True";
else
	echo "False";

Who does that else belong to? Top if or bottom if.... oh no, maybe it's both!

PLACE BETS NOW!

LoganK

I see what you mean...in this case I'd say "top" for $25 😃

But if we ignore that and correctly put an else statement in, then you're saying that the PHP will run fine and produce the expected result?

Drakla

It'll run fine as it is. But its expected behaviour - oOoOooo mystery of delights only solvable by big php master at Zend temple. That or running it with different $foo / $bar values.

halojoy

<?php

// using curly parantes for clarity

if ($foo == true)
{
    if ($bar == true)
    {
        echo "True";
    }
}

else
{
    echo "False";
}


// with 'normal coding' to do the same ( && = AND )

if($foo==true && $bar==true) echo "True";
else echo "False";

?>

isnt this last code the nicest ..

hehe,
that is what halojoy thinks,
but what does he know

😃

Weedpacket

echo ($foo && $bar) "True" : "False";

Drakla

Weedpacket wrote:
echo ($foo && $bar) "True" : "False";

echo ($foo && $bar) ? "True" : "False";

Question mark missing.

LoganK

Halojoy, I realized I could've done that. And Weedpacket, I know all about the ternary operators. I know that those could be used and most often I do use them. However, I've thought of this problem before and thought, "what would happen?". From the looks of it, I think people are agreeing to disagree 😃.

I'll need to wait until my laptop comes back, and I'll test it on there. Thanks for all your help! The thread is resolved!

laserlight

Anyway, back to the original question.
methinks the answer is:

if ($foo == true)
	if ($bar == true)
		echo "True";
	else;
else
	echo "False";

Though realistically this is just asking for trouble 🙂

LoganK

Didn't know you could do an "else" like that with a semicolon.

Allright, thanks for all the help guys!

laserlight

Didn't know you could do an "else" like that with a semicolon.

I thought of it from Python's pass statement, but it is used occasionally in loops, e.g.
while (condition);
where the condition consists of say, a function that will eventually return false.

Drakla

Hopefully all this is just academic anyway. I do use single line if / else (any make sure nobody from PEAR is watching) but if it goes beyond the blatantly obvious then put some braces on or your php trousers might fall down in front of a vicar.

For those outside Britain, 'braces' are what Americans call 'suspenders', but what we call suspenders are them sexy lady things for holding up tights... which Americans call pantyhose... which to use means.... (etc, etc)

LoganK

Laserlight - Thanks for clearing it up.

Drakla - I'm amazed at the inconsistencies and misunderstandings between two countries that both speak English. I'm an American, so when you said braces and trousers and suspenders and...you get what I mean 😃