Need help finding what's wrong with this code?

Question

I did an exercise in my programming class about a pi calculator using the German mathematician Gottfried Leibniz's method to approximate pi: pi/4 = 1 - 1/3 + 1/5 - 1/7 + . . .
This is my code:
import java.util.Scanner;

public class Pi
{
    public static void main(String[]args)
    {
        Scanner reader = new Scanner(System.in);
        double pi = 1;
        int denominator = 3;
        int count = 0;
        int sign = 0;
        System.out.print("Enter the number of cycles: ");
        int cycles = reader.nextInt();
        System.out.println(cycles);
        while(count <= cycles)
        {
            if(sign == 0)
            {
                pi = pi - (1 / denominator);
                denominator = denominator + 2;
                sign = 1;
                count++;
            }
            else
            {
                pi = pi + (1 / denominator);
                denominator = denominator + 2;
                sign = 0;
                count++;
            }
        }
        System.out.println(pi * 4);
    }
}
It looks like it should work, but no matter what the input is I always get 4. Not even my classmate who's practically a genius at programming nor the teacher know what's wrong. I'm not being graded on this but I just need to know what's wrong.

meet · Accepted Answer

the problem is idiotic.....u'll die laughing.

declare denominator as a double and not int.
i realised that java is truncating the denominator to an integer if it is an int.
so 1/denominator is always 0 and pi never changes. thats why u got 4 in the end

modulo_function · Answer

When you say
(1/denominator)

and denominator is an int, the result will be truncated.  Either change denominator to double or use
1.0/denominator

+add
You didn't ask but I'll suggest an easier way to get that sign change:

int sign = -1.0;
while( count < cycles ) {
...pi = pi + sign*(1.0/denominator);
...denominaor = denominator + 2;
...sign = -1*sign;
...count++;
}

Trending News

Need help finding what's wrong with this code?

2 Answers