why won't this math work?

Question

I'm trying to run a loop that goes 1 + 1/3 + 1/5 - 1/7 + 1/9....so on

but it keeps coming up as 1!

I have tried

double answer = 1 + 1/3 + 1/5 - 1/7 + 1/9 - 1/11;
displays 1

the math is weird like I even messed around and tried

double answer = 1 / 5; //should display 0.2
displays 0!!!!!!!!

Answer 1

You are using integer math.

The result of an operation between two integers will be an integer, rounded towards 0.

So your code becomes:

double answer = 1 + 0 + 0 - 0 + 0 - 0;

Try this instead.

double answer = 1.0 + 1.0/3.0 + 1.0/5.0 - 1.0/7.0 + 1.0/9.0 - 1.0/11.0;

Answer 2

Because you are using integer literals. Try this:

double answer = 1 + 1/3.0 + 1/5.0 - 1/7.0 + 1/9.0 - 1/11.0;

Answer 3

In C++, when you divide one integer by another, you get an integer. Thus, 1/3 equals 0.

Try:

double answer = 1 + 1/3.0 + 1/5.0 - 1/7.0 + 1/9.0 - 1/11.0;

Answer 4

The operation work on integer constants, then result is converted to double. You should define your constants as follows:

double answer = 1.0 + 1.0/3.0 + 1.0/5.0 - 1.0/7.0 + 1.0/9.0 - 1.0/11.0;

Answer 5

Try 1.0/3.0, etc.

Otherwise, each sub-expression will evaluate to 0 as they are interpreted as integers.