Thread: Trouble finding correct value

Hey all, I know this is a newb question here but I'm having trouble finding the answer to this equation posed in one of my past year exam scripts.

Code:

int z, x = 5, y = -10, a = 4, b = 2; 
//x = 5
//y = -10
//a = 4
//b = 2

z = x++ - --y * b / a;

When I solve this equation I get an answer of 0 (zero) but when I put it in the compiler, the value returned is 10.

Heres how I solved it:

z = x++ - (--y) * b / a;
z = 5++ - (--(-10)) * 2 / 4;
z = 6 - (-11) * 2 / 4;
z = 6 - (-11) * 0 // at this point 2/4 yields 0 correct?
z = 6 + 11 * 0
z = 0;
but I am sadly mistaken as the answer is 10 according to the compiler.
Can any one help me out here?
Please and thank you. Any feedback is greatly appreciated.

Originally Posted by bernt

This increments x after the expression is evaluated.

Y is decremented first, then multiplication and division are done in one go, left to right.


ORDER OF OPERATIONS!!!

Ten is what I got, btw.

Thank you thank you, I finally got 10.

x++ - --y * b / a;
5 - (-11) * 2 / 4;
5 - (-22)/4
5 - (-5)
= 5 + 5 = 10.

Code:

z = 5++ - (--(-10)) * 2 / 4;

That is not a legal C++ statement.

Originally Posted by Memloop

Code:

z = 5++ - (--(-10)) * 2 / 4;

That is not a legal C++ statement.

I just wrote that to denote the brackets, to help visualise that (-10) would have been decremented.