Trouble with calling method [duplicate]

问题

This question already has answers here:

Fahrenheit to Celsius conversion yields only 0.0 and -0.0 (5 answers)

Closed 5 years ago.

public static void main (String[] args) {

   for (double f=0; f<=20;f++) {
      System.out.println(f+":Degrees Fahrenheit converted to Celsius = "+ celsius(f));
   }
}

public static double celsius (double fahrenheit) {
    double cels=(fahrenheit-32)/(5/9);
    return cels;
}

With this program I'm trying to convert Fahrenheit to Celsius, and when I call method Celsius to my main when I run the program the end result for Celsius is always -infinity. What am I doing wrong?

回答1:

You're doing int division which always returns an int. For example 5/9 returns 0.

Instead use double division 5.0/9.0

For your code:

public static double celsius (double fahrenheit) {
    return (fahrenheit - 32) / (5.0 / 9.0);
}

We should probably close this question as a duplicate as it's been asked many many times. For example: fahrenheit-to-celsius-conversion-yields-only-0-0-and-0-0

回答2:

(5/9) is an integer division, it always returns 0.

It should be: (5.0/9.0)

来源：https://stackoverflow.com/questions/19690271/trouble-with-calling-method