Chapter 5 - Program Looping

[skochan]

This is a 10 question quiz.

Chapter 5 Quiz.

[amuso]

These quizes are great. I myself have learned a few things by taking them. Thanks for making them for us.

I have a slight problem with one of the questions in this quiz though. So here is a really newbie question

You ask what the output from the following code is:

Code: (Objective-C)

for (int i=5, x=0; i>0; --i)
   x -= i;

NSLog (@"%i", x);

While I finally understood what the result would be, I had problems at first doing it in my head. So I pasted into Xcode to see if I did it right. However Xcode didnt like this and complained x was not initalized. So actually it doesnt produce a result. But by changing the code a bit I got it right.

Code: (Objective-C)

int x, i;
for (i=5, x=0; i>0; --i)
   x -= i;

NSLog (@"%i", x);

But was your intention to throw us off with the forcing of the type integer, or was it intended to declare the variables x and i in the for-loop ?

[skochan]

No, that's my fault.  In the example, since x and i are declared in the start of the for loop, their scope is limited to the loop.   So x and i both go out of scope (and are therefore flagged as undeclared) when the loop is done.

Cheers,

Steve Kochan