In simplest terms, truncation means to chop off the decimal portion of a number. A method of approximating a decimal number by dropping all decimal places past a certain point without rounding.
Given a double value and a decimal place truncate the value to the given decimal point.
Example:
Input: val = 3.142857142857143 Decimal point = 3 Output = 3.142 Upto 3 decimal places
Approach 1: Using Mathematically :
- Shift the decimal of the given value to the given decimal point by multiplying 10^n
- Take the floor of the number and divide the number by 10^n
- The final value is the truncated value
Java
// Java program to truncate the double value to// a particular decimal point import java.io.*; class GFG { static void change(double value, int decimalpoint) { // Using the pow() method value = value * Math.pow(10, decimalpoint); value = Math.floor(value); value = value / Math.pow(10, decimalpoint); System.out.println(value); return; } // Main Method public static void main(String[] args) { double firstvalue = 1212.12131131; int decimalpoint = 4; change(firstvalue, decimalpoint); double secondvalue = 3.142857142857143; int decimalpoint2 = 3; change(secondvalue, decimalpoint2); }} |
Output
1212.1213 3.142
Approach 2: Using String matching approach
- Convert the number into String
- Start the counter variable when “.” found in the String
- Increment the counter till decimal point
- Store the new String and parse it in double format
Java
// Java program to truncate the double// value using string matching import java.io.*; class GFG { public static void main(String[] args) { double firstvalue = 1212.12131131; // decimal point int decimalpoint = 6; // convert the double value in string String temp_value = "" + firstvalue; String string_value = ""; int counter = -1; for (int i = 0; i < temp_value.length(); ++i) { // checking the condition if (counter > decimalpoint) { break; } else if (temp_value.charAt(i) == '.') { counter = 1; } else if (counter >= 1) { ++counter; } // converting the number into string string_value += temp_value.charAt(i); } // parse the string double new_value = Double.parseDouble(string_value); System.out.println(new_value); }} |
Output
1212.121311
