How to fix computation errors?

Question

I'm trying to write a program that reads 2 numbers from the user and divides them. Here is the code I have so far:

import java.util.Scanner;

public class divideByZero {

public static int quotient(int numerator, int denominator)
{
   return numerator / denominator;
}

public static void main(String args[])
{
   Scanner scanner = new Scanner(System.in);

    System.out.print("Please enter the first number: ");

    int numerator = scanner.nextInt();

    System.out.print("Please enter the second number: ");

    int denominator = scanner.nextInt();

    int result = quotient( numerator, denominator );

    float result2 = (float)result;

    System.out.printf("\n The first number %d divided by the second number "
            + "%d = %f\n", numerator, denominator, result2 );

}

I'm having problems with the computations. For example, when I enter 3 divided by 4, I get the result 0.000000. How do I get the correct result to 2 decimal places?

Answer 1

Cast the numerator and denominator as floats before you divide them.

import java.util.Scanner;

public class divideByZero {

public static float quotient(float numerator, float denominator)
{
   return numerator / denominator;
}

public static void main(String args[])
{
   Scanner scanner = new Scanner(System.in);

    System.out.print("Please enter the first number: ");

    int numerator = scanner.nextInt();

    System.out.print("Please enter the second number: ");

    int denominator = scanner.nextInt();

    float result = quotient( (float) numerator, (float) denominator );

    System.out.printf("\n The first number %d divided by the second number "
            + "%d = %f\n", numerator, denominator, result );

}

Answer 2

The following changes will do what you need.

public static float quotient(int numerator, int denominator)
{
    return (float)numerator / (float)denominator;
}

float result = quotient( numerator, denominator );

System.out.printf("\n The first number %d divided by the second number "
        + "%d = %.2f\n", numerator, denominator, result2 );

You cannot do division on an int and get a fractional int (there is no such thing), so the division must be done with floats and stored into a float. The %.2f limits it to 2 decimal places.

Answer 3

Why don't you use the datatype double instead of float?

Here is some code to format into two decimal points:

import java.text.*;

public class DecimalPlaces {

   public static void main(String[] args) {

       double d = 1.234567;
       DecimalFormat df = new DecimalFormat("#.##");
       System.out.print(df.format(d));
   }

}

Answer 4

You are getting 0.0000 because you are dividing integer numbers and storing that result back into an integer. To see the fractional part, you can declare result to be a float variable.

When that's working, to print 2 decimals you can use printf formatting.

In C it'd be something like %.2f.

Based on the errors, I think you'd benefit from reading about data types, especially floating point numbers.

Answer 5

If you change the return type of the quotient method from an int to a float, it will no longer round the answer to the nearest integer.

public static float quotient(int numerator, int denominator)
{
   return (float) numerator / (float) denominator;
}