Thread: Trouble With Doubles

No rhyme intended.

import java.util.Scanner;
 
public class CalculatorProgram {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		double firstNumber, secondNumber, answer;
 
		System.out.println("Enter the first number:");
		firstNumber = input.nextDouble();
 
		System.out.println("Enter the second number:");
		secondNumber = input.nextDouble();
 
		answer = firstNumber + secondNumber;
		System.out.println(answer);
	}
}

When given two doubles, this code occasionally gives an answer that is incorrect (unless I'm seriously overlooking something math-wise). For instance, I gave it 23.2 and 26.4 and it gave an answer of 49.599999999999994. Can you think of any reason why the answer is not a double and also incorrect?

I feel really stupid having to have a primitive type defined, but then what exactly is a double? I thought it was a number with a decimal point rounded to the second decimal place.

Also, why does floating point notation lead to errors? I could understand in very large numbers, but for numbers with only two decimal points?

Some time invested on your favorite search engine would better answer your question than a forum. Spend some time looking up double and there are many lengthy explanations about what happens. Did you try the link posted by helloworld922 above? If not, read that. Also read this.

Ok, thanks for the help everyone. This one is solved now.