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Java: scanner reads integer but does not use it during / for loop

My book I am studying uses a different library for reading Inputs, so it cannot help me.

I can't see where my mistake is. Algorithm:

  • Read the value n
  • Set value i to 3
  • Follow steps

Iteration

While i < 2*n

       i+1

       Write 1/(2*i+1) to the console.

My code:

import java.util.Scanner;

public class Aufgabe420 {
public static void main (String[] args) {
int i, n; 

    System.out.println("Please enter a number!");
    Scanner sc = new Scanner(System.in);
    n = sc.nextInt();
    System.out.println("n ="+n);
    System.out.println("The while-loop starts!");
    i = 3;
    while (i < 2*n){
        i += 1;
        System.out.println(1/(2*i+1));
    }

        System.out.println("now with for-loop");    

    for (i = 3; i < (2*n); i+=1) {
        System.out.println(1/(2*i+1));
    }


    }
}

But after trying it results in: Please enter the number! five

n = 5 The while loop starts! 0 0 0 0 0 0 0

now with for-loop 0 0 0 0 0 0 0

What's wrong with this code? Thanks for your help.

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2 answers


1/(2*i+1)

will result in 0 for any positive i

, since 1 <(2 * i + 1) and int division cannot result in a fraction.

change

System.out.println(1/(2*i+1));


to

System.out.println(1.0/(2*i+1));

You want to do floating point division, not int.

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This line

System.out.println(1/(2*i+1));

has a problem that it does integer division. And 1 divided by any value greater than 1 will always be 0. Solution: One of the operands must be a float for the result to be floating, for example. eg:



System.out.println(1.0/(2*i+1));

or do the following:

System.out.println(1/(float)(2*i+1));
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