I'm trying to determine the number of digits to the left and the right of the result by...(Java)

Question

using Double.toString(result), indexOf('.') to find the position of the decimal, and length() to find the length. This is what I have so far.

import java.util.Scanner;

public class FormulaEvaluator {

   public static void main(String[] args) {

      double x;
      double discriminant, result;

      Scanner userInput = new Scanner(System.in);
      System.out.print("Enter a value for x: ");
      x = userInput.nextDouble();
      discriminant = 8 * Math.pow(x, 4) - (6 * Math.pow(x, 3)) 
         + +(4 * Math.pow(x, 2)) + Math.abs(20 * x) + 1;
      result = Math.pow(9 * Math.pow(x, 3) + (7 * Math.pow(x, 2)) 
         + +(5 * x) + 3, 2) * Math.sqrt(discriminant); 

      System.out.println("Result: " + result);
   }
}

Answer 1

First get the length of result.

int resultLength = Double.toString(result).length();

Then get the index of the decimal point.

int decimalIndex = Double.toString(result).indexOf('.');

Then subtract the index from the result length to get the number of decimal places after the decimal.

int numPlacesAfterDecimal = resultLength - decimalIndex;

The index of the decimal place happens to be the number of places to the left of the decimal.

int numPlacesBeforeDecimal = decimalIndex;

Edit: Edited variable names for better consistency.