[Resolved] looping code

gilk9

I want to tighten this code up to be less clumsy.
The code checks 25 questions and answers and increments the number of wrong answers if found.
Submitted answers $POST[a1] to $POST[a25]
Correct answers $r1 to $r25
The code actually works as is, but it obviously needs improving!
Thanks in anticipation....
gilk9 a very new newbie.
//then compare answers

     $wrong_answers = 0;    // initialise to zero

                 if  ($_POST[a1] != $r1) {
      $wrong_answers += 1;
                }
                 if  ($_POST[a2] != $r2) {
      $wrong_answers += 1;
                }
                 if  ($_POST[a3] != $r3) {
      $wrong_answers += 1;
                }
                 if  ($_POST[a4] != $r4) {
      $wrong_answers += 1;
                }
                 if  ($_POST[a5] != $r5) {
      $wrong_answers += 1;
                }
   //etc etc etc up to 25 times!!

I have tried the following:-

for ($i = 1; $i < 26; $i++) {
if ($_POST[a{$i}] != $r{$i}) { //LINE 52
++$wrong_answers;
}
}

but I get error:-
Parse error: parse error, unexpected '{', expecting ']' in /html/myphpfile.php on line 52 (asterisked above).

Can anyone advise on this looping structure?
gilk9

bradgrafelman

It's not liking that $r{$i} business. Try using this instead:

if ($_POST[a{$i}] != ${'r'.$i}) { //***LINE 52***

EDIT: Forgot to explain what I did! Heh.

Basically, in my change, you're creating a string inside the brackets, and telling PHP to look for a variable called that. In your code, you gave part of the variable name, then tried to have PHP evaluate some code that should be appended.

It probably doesn't make sense anywhere in my mind, but at any rate, I don't think you can specify part of a variable name, then have PHP evalulate code to add on to the variable name. That's why I had the 'r' inside the brackets, so that the $i is appended to 'r', therefore giving you the entire variable name.

Clear as mud, right?

gilk9

you da man Brad.
Thanks very much.....I plugged your correction in and it works a treat.
Clear as mud...Yes!
But I will read it your comments thoroughly and see if I can get my head around it.
ta.

Installer

I think the post index would be like this:

$_POST['a' . $i]

The other way should also be giving a parse error.

bradgrafelman

Nice catch! Yes, indeed, that should also be fixed :p

if ($_POST['a' . $i] != ${'r'.$i}) { //***LINE 52***

gilk9

yeah I looked at that, but not being an expert I accepted it and plugged it in and it worked!!!
Then later when I went back to it it didnt....much pulling of hair etc!
It wasnt till I went back to the forum to check that I had copied the code correctly that I found that there had been an amendment.
It now works again with the amended code.....something spooky here because it worked when half fixed for a while....cant understand that.

fingers crossed
gilk9