[Nigo]

public class Centigrade_Fahrenheit
{
	public static void main(String[] args)
	 {
		int start = 0;
		final int end = 20;

		System.out.println("Centigrade \t Fahrenheit");
		System.out.println("------------------------------");
		while(start <= end)
		 {
			double fahrenheit = (9/5) * start + 32;
			System.out.println(start + "\t\t" + fahrenheit);
		 	start++;
		 }
	   }
}

very quick code to display 0 to 20 centigrade degree and show its equivalents in fahrenheit. It work.. my program farenheit is like 9 or 8 degree off though. I notice in my program the farenheit show up as (33.00) instead of (33.8). what do i need to do to make the caculation more precise?

[Tanira]

Nigo, on 30 Jun, 2009 - 08:09 AM, said:

public class Centigrade_Fahrenheit
{
	public static void main(String[] args)
	 {
		int start = 0;
		final int end = 20;

		System.out.println("Centigrade \t Fahrenheit");
		System.out.println("------------------------------");
		while(start <= end)
		 {
			double fahrenheit = (9/5) * start + 32;
			System.out.println(start + "\t\t" + fahrenheit);
		 	start++;
		 }
	   }
}

very quick code to display 0 to 20 centigrade degree and show its equivalents in fahrenheit. It work.. my program farenheit is like 9 or 8 degree off though. I notice in my program the farenheit show up as (33.00) instead of (33.8). what do i need to do to make the caculation more precise?

Change 9/5 to 1.8

The reason is java takes 9/5 and rounds it. 9.0/5 or 9/5.0 would also fix it.

This post has been edited by Tanira: 30 June 2009 - 09:17 AM

[kmangold]

double fahrenheit = (9 * start) / 5 + 32;

[xclite]

You are performing integer mathematics. You can either case start as a double, like:

  double fahrenheit = (9/5) * (double) start + 32

Or just make a double to start with. You'll want to make it 9.0/5 also, or you'll only get an integer for that.

kmangold, on 30 Jun, 2009 - 12:15 PM, said:

double fahrenheit = (9 * start) / 5 + 32;

This solution will not get you the correct answer: 9 * start / 5 will perform integer, not real, division.

[kmangold]

Very true. It's still a lot closer than what the original poster had in the beginning. This is what they get for half effort in finding the answer on their own, a half a decent response.

[xclite]

kmangold, on 30 Jun, 2009 - 12:21 PM, said:

Very true. It's still a lot closer than what the original poster had in the beginning. This is what they get for half effort in finding the answer on their own, a half a decent response.

I wouldn't exactly call it a half effort, it simply seems that the OP was not aware of how java does integer division. It's an honest mistake that a lot of people make. The logic in the program is sound.

[kmangold]

There are so many examples already online that does celcius to fahrenheit conversion...

[xclite]

kmangold, on 30 Jun, 2009 - 12:26 PM, said:

There are so many examples already online that does celcius to fahrenheit conversion...

There are, but I would rather have somebody explain to me what I was doing wrong than have to look at an example that just works and hope I can find what I did differently. If there are examples of things online, why does anybody go to school, anyway?

[Fuzzyness]

If there are soo many examples.. Why did you get it wrong answer anyways? Just because something is"closer" then what they had, doesn't mean you should post it.

Quote

It's still a lot closer than what the original poster had in the beginning.

Most people post on here ask for help because they don't understand something, last thing they need is to be misleaded because you felt like posting the "closest" thing.


As for Nigo-

Like everyone said what you were getting was Integer division.
10/3 = 3 <-- the / sign will tell you how many times goes into it. Will NOT give you a remainder. if it doesnt go into it at all, will be 0. Dividing 2 integers will give you integer Division if there is supposed to be a decimal

2/3 <-- that is 0, 3 cannot go into it.

10 % 3 = 1 <--- the % sign will give you the remainder.

Also, Integer division occurs because there is supposed to be a remained, and you not getting it because dividing by an int. So, you can do 1 of 2 things.

1. Cast as a double (double) 9/5

2. Make one of the numbers a double by adding a .0 9.0/5 or 9/5.0


Hope this helps!

This post has been edited by Fuzzyness: 30 June 2009 - 09:45 AM

[kmangold]

OMG! I gave credit to xclite! I admitted I was wrong! Let it go! I didn't post it because I thought it was closer, I overlooked the fact that it was integer math!

[xclite]

kmangold, on 30 Jun, 2009 - 12:43 PM, said:

OMG! I gave credit to xclite! I admitted I was wrong! Let it go! I didn't post it because I thought it was closer, I overlooked the fact that it was integer math!

Except that in every instance where you "gave somebody credit" for having a more proper solution, you have to throw in an insult or a snide comment so that you don't take some perceived pride hit. See the other thread about integers from 0 to 9 for another example of that. You could have just said "Oh, I forgot about integer math," instead you accused the OP of being lazy and said there were solutions on the internet.

[NeoTifa]

Okaaayyyyyyy..... Everyone is so testy today.....


It looks like your variables are all ints. No matter how you divide them they will always come out whole numbers.

[Fuzzyness]

NeoTifa, on 30 Jun, 2009 - 08:50 AM, said:

Okaaayyyyyyy..... Everyone is so testy today.....


It looks like your variables are all ints. No matter how you divide them they will always come out whole numbers.

More like grouchy Just woke up lol

I have actually never used floats or longs before in Java. Is there a similiar problem with those as there is with mathmatical operations or is it pretty much just integers?

[xclite]

Fuzzyness, on 30 Jun, 2009 - 12:54 PM, said:

More like grouchy Just woke up lol

I have actually never used floats or longs before in Java. Is there a similiar problem with those as there is with mathmatical operations or is it pretty much just integers?

A long will act like an int in division, a float like a double, if I understand your question correctly. Is that what you were asking?

[Fuzzyness]

Yeah it was. Never used those types before, haven't seen a problem where I would need to. Thanks for the answer

Yay for hi-jacking a forum!