Temperature Convertions

问题

I have to convert a temperature in degrees Celsius to Fahrenheit. However when I print the temperature in Celsius I get the wrong answer ! Please help ! (The formula is c = (5/9) * (f -32). When I type in 1 for degrees farenheit I get c = -0.0. I have no idea what is wrong :s

Here is the code

import java.io.*; // import/output class
public class FtoC { // Calculates the temperature in Celcius
    public static void main (String[]args) //The main class
    {
    InputStreamReader isr = new InputStreamReader(System.in); // Gets user input
    BufferedReader br = new BufferedReader(isr); // manipulates user input
    String input = ""; // Holds the user input
    double f = 0; // Holds the degrees in Fahrenheit
    double c = 0; // Holds the degrees in Celcius
    System.out.println("This program will convert the temperature from degrees Celcius to Fahrenheit.");
    System.out.println("Please enter the temperature in Fahrenheit: ");
    try {
        input = br.readLine(); // Gets the users input
        f = Double.parseDouble(input); // Converts input to a number
    }
    catch (IOException ex)
    {
        ex.printStackTrace();
    }
    c = ((f-32) * (5/9));// Calculates the degrees in Celcius
    System.out.println(c);
    }
}

回答1:

You are doing integer division, and hence 5 / 9 will give your 0.

Change it to floating point division: -

c = ((f-32) * (5.0/9));

or, do the multiplication first (Remove the brackets from division): -

c = (f-32) * 5 / 9;

Since, f is double. Numerator will be double only. I think this way is better.

回答2:

use this rather:

c = (int) ((f-32) * (5.0/9));// Calculates the degrees in Celcius

as it involves division and you should not use only ints to get proper division

回答3:

Use this

System.out.println((5F / 9F) * (f - 32F));

回答4:

You should try using double instead of int as this would lead to loss of precision. Instead of using the whole formula, use one calculation at one time

Example: Use appropriate casting Double this = 5/9

F - Double 32

回答5:

Unless explicitly specified otherwise, Java treats all numbers as integers. Since integers cannot store fractional parts of numbers, when integer division is performed, the remainder is discarded. Therefore: 5/9 == 0

Rohit's solution c = (f-32) * 5 / 9; is probably the cleanest (though the lack of explicit types may cause a bit of confusion).

来源：https://stackoverflow.com/questions/13946711/temperature-convertions

标签

java

temperature