# the x value

• 11-07-2002
Absy
the x value
assuming x is = 10.0
why after this assignment x becomes 210.0

x = x - 20.0

• 11-07-2002
Sebastiani
Well, what's the variables type?
• 11-08-2002
RoD
Re: the x value
Quote:

Originally posted by Absy
assuming x is = 10.0
why after this assignment x becomes 210.0

x = x - 20.0

I'll assume that they are doubles scince u have the decimal.

I believe it would be

x = 190.0

Scince x was redefined as 210.0 you just subtract the 20.0 from that as the 10.0 is no longer in the equation.
• 11-08-2002
PJYelton
I think Absy meant it became 210 AFTER the equation x=x-20.0

Somewhere between x=10.0 and x=x-20.0 you have code that is changing the value of x. Post all the code between these two statements and we'll help ya track it down!
• 11-08-2002
Absy
sorry for the confusion
Sorry if I confused you all,
Actually it was a question in one of the chapters Iread,and the question is like like this:

what value is assigned to x by the statement below assuming x is
10.0?

x = x - 20.0;

when I checked the answer at the end of the chapter it was
210.0
I just want to understand why is the answer like that and they did not mention what type the variable is or there is no more code lines thanks again.
• 11-08-2002
Eibro
I'm guessing the value loops back around...
eg.

unsigned char mychar = 0;
mychar -= 10;

mychar should now equal 245, as 255 is the max value for a char, and subtracting 10 from the min value (0) is going to give you 10 less than the max value. However, I can't think of any variable which has a max value of 220...

What book is this?
• 11-08-2002
OneStiffRod
It's probably a typo, the answer is -10.0 The 2 was probably printed instead of the -
• 11-08-2002
Absy
the value of x
the book is " problem solving abstraction design using C++"
by frank l. friedman and elliot b. doffman
it is a text book in Penn State Univ. capitol campus