Programming Forums > Application Development > Java

shangnyun · Jun 9th, 2005, 8:54 AM

I am soooooo lost!

Here's the assignment: "Write a program that allows the user to convert either from degrees Celsius to Fahrenheit or from degrees Fahrenheit to Celsius. In a loop, prompt the user to enter a temperature (as an integer). In a nested loop, prompt the user to enter a letter for Celsius or Fahrenheit. Use a switch statement to analyze the user input and to request to reenter the letter (but not the temperature) in case of invalid input. Print the result of conversion as a double and prompt the user to choose to continue or to quit."

More details from the book assignment: "Write a program that allows the user to convert either from degrees Celsius to Fahrenheit or from degrees Fahrenheit to Celsius. Use the following formulas:

degreesC = 5(degreesF = 32)/9
degreesF = (9(degreesC)/5) + 32

Prompt the user to enter a temperature and either a 'C' (or 'c') for Celsius or an 'F' (or 'f') for Fahrenheit; allow either uppercase or lowercase, but if anything other than 'C', 'c', 'F', or 'f' is entered, print an error message and ask the user to reeneter a valid selection (uppercase or lowercase 'C' or 'F'). Convert the temperature to Fahrenheit if Celsius is entered, or to Celsius if Fahrenheit is entered, and then ask the user to press 'Q' or 'q' to quit or to press any other key to repeat the loop and perform another conversion."

(Toggle Plain Text)

import java.util.*;

public class TempConversion
{
    public static void main(String[] args)
    {
    	int degreesC, degreesF;
    	
    	System.out.println("=====TEMPERATURE CONVERSION=====");
    	System.out.println();
    	System.out.println("Please enter a whole number for");
    	System.out.println("conversion:");
    	
    	Scanner keyboard = new Scanner(System.in);
    	
    	
    	degreesC = keyboard.nextInt();
    	degreesF = keyboard.nextInt();
    }
}

This is how far I am. Not far at all, in other words. I desperately need help on this one

Thanks

shangnyun · Jun 9th, 2005, 9:09 AM

I don't understand why it says "in a loop, prompt the user to enter a temperature (as an integer)"... isn't what I've come up with above perfectly sufficient for this first user-input?

Knight · Jun 9th, 2005, 9:15 AM

You have no loops in your code. That is your first problem. There are different types of loops, i.e. for while do-while etc... Try those and see what you come up with.

shangnyun · Jun 9th, 2005, 9:18 AM

Working on it. I just don't understand why I'm supposed to use a loop just so the user can enter an integer..

Berto · Jun 9th, 2005, 9:19 AM

also ask the user which conversion they require?

HeX · Jun 9th, 2005, 9:21 AM

are you allowed to use JOptionPane ? if yes then:

(Toggle Plain Text)

import java.util.*;

public class TempConversion
{
    public static void main(String[] args)
    {
	double result;
	String degree;
	int input;
    	
	degree = JOptionPane.showInputDialog("Enter: \n C - Fahrenheit to Celsius\n F - Celsius to Fahrenheit");


	input = new Integer(JOptionPane.showInputDialog("Enter the degree:")).intValue();

	if(degree == "C" || degree == "c")
	{
			result = 5.0/9.0 * (input - 32);
			System.out.println(input + " Fahrenheit is " + result + " Celsius");
	}
	else if(degree == "F" || degree == "f")
	{
		result = 9.0/5.0 * input + 32;
		System.out.println(input + " Celsius is " + result + " Fahrenheit");
	}
	
    }
}

shangnyun · Jun 9th, 2005, 9:24 AM

No.. we are not doing Swing at all. But thanks.. that helped somewhat

Knight · Jun 9th, 2005, 9:32 AM

Quote:

Originally Posted by shangnyun

Working on it. I just don't understand why I'm supposed to use a loop just so the user can enter an integer..

I think they're trying to teach you how to handle invalid input. You don't want your *strong deep voice* huge immensely powerful super program *end strong deep voice* that you worked on for months and cost the company thousands or millions of dollars (heh, millions..right..) to crash because of a simple invalid input (scenario for when you are working for a major corporation or something). Its just a simple check to make sure the input is valid so your program can function correctly later on.

shangnyun · Jun 9th, 2005, 9:51 AM

Quote:

Originally Posted by HeX

are you allowed to use JOptionPane ? if yes then:

(Toggle Plain Text)

import java.util.*;

public class TempConversion
{
    public static void main(String[] args)
    {
	double result;
	String degree;
	int input;
    	
	degree = JOptionPane.showInputDialog("Enter: \n C - Fahrenheit to Celsius\n F - Celsius to Fahrenheit");


	input = new Integer(JOptionPane.showInputDialog("Enter the degree:")).intValue();

	if(degree == "C" || degree == "c")
	{
			result = 5.0/9.0 * (input - 32);
			System.out.println(input + " Fahrenheit is " + result + " Celsius");
	}
	else if(degree == "F" || degree == "f")
	{
		result = 9.0/5.0 * input + 32;
		System.out.println(input + " Celsius is " + result + " Fahrenheit");
	}
	
    }
}

OMG... you helped me but also confused the shit out of me. I totally understand your logic in using only one variable for the degree integer, namely "input", but I'm confused why my book is using TWO variables, namely degreesC and degreesF.
And this is without Swing, so no JOptionPane

Knight · Jun 9th, 2005, 10:05 AM

The only reason I could think of why they have (2) variables is that, if you want to use the degreeF later on and you initially converted to degreeC, you just have to use the degreeF variable (which means you don't have to reconvert it again). So, I would stick this in the beginning:

(Toggle Plain Text)

// if they input it in farenheit first

degreesC = 5.0/9.0 * (input - 32);
degreesF = input;

//if they input it in celsius first
degreesF = 9.0/5.0 * input + 32;
degreesC = input;

That way, if you need the temperature in Farenheit, you could just use the variable degreesF and vice versa

Jun 9th, 2005, 8:54 AM	#1
shangnyun Programmer Join Date: Jun 2005 Posts: 34 Rep Power: 0	Temperature Conversion Program - Help! I am soooooo lost! Here's the assignment: "Write a program that allows the user to convert either from degrees Celsius to Fahrenheit or from degrees Fahrenheit to Celsius. In a loop, prompt the user to enter a temperature (as an integer). In a nested loop, prompt the user to enter a letter for Celsius or Fahrenheit. Use a switch statement to analyze the user input and to request to reenter the letter (but not the temperature) in case of invalid input. Print the result of conversion as a double and prompt the user to choose to continue or to quit." More details from the book assignment: "Write a program that allows the user to convert either from degrees Celsius to Fahrenheit or from degrees Fahrenheit to Celsius. Use the following formulas: degreesC = 5(degreesF = 32)/9 degreesF = (9(degreesC)/5) + 32 Prompt the user to enter a temperature and either a 'C' (or 'c') for Celsius or an 'F' (or 'f') for Fahrenheit; allow either uppercase or lowercase, but if anything other than 'C', 'c', 'F', or 'f' is entered, print an error message and ask the user to reeneter a valid selection (uppercase or lowercase 'C' or 'F'). Convert the temperature to Fahrenheit if Celsius is entered, or to Celsius if Fahrenheit is entered, and then ask the user to press 'Q' or 'q' to quit or to press any other key to repeat the loop and perform another conversion." (Toggle Plain Text) import java.util.; public class TempConversion { public static void main(String[] args) { int degreesC, degreesF; System.out.println("=====TEMPERATURE CONVERSION====="); System.out.println(); System.out.println("Please enter a whole number for"); System.out.println("conversion:"); Scanner keyboard = new Scanner(System.in); degreesC = keyboard.nextInt(); degreesF = keyboard.nextInt(); } } import java.util.; public class TempConversion { public static void main(String[] args) { int degreesC, degreesF; System.out.println("=====TEMPERATURE CONVERSION====="); System.out.println(); System.out.println("Please enter a whole number for"); System.out.println("conversion:"); Scanner keyboard = new Scanner(System.in); degreesC = keyboard.nextInt(); degreesF = keyboard.nextInt(); } } This is how far I am. Not far at all, in other words. I desperately need help on this one Thanks

Jun 9th, 2005, 9:19 AM	#5
Berto Programming Guru Join Date: Aug 2004 Posts: 1,022 Rep Power: 5	also ask the user which conversion they require? __________________ "Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity." - Albert Einstein

Jun 9th, 2005, 9:21 AM	#6
HeX Programmer Join Date: May 2005 Location: Kosova Posts: 94 Rep Power: 4	are you allowed to use JOptionPane ? if yes then: (Toggle Plain Text) import java.util.; public class TempConversion { public static void main(String[] args) { double result; String degree; int input; degree = JOptionPane.showInputDialog("Enter: \n C - Fahrenheit to Celsius\n F - Celsius to Fahrenheit"); input = new Integer(JOptionPane.showInputDialog("Enter the degree:")).intValue(); if(degree == "C" \|\| degree == "c") { result = 5.0/9.0 (input - 32); System.out.println(input + " Fahrenheit is " + result + " Celsius"); } else if(degree == "F" \|\| degree == "f") { result = 9.0/5.0 * input + 32; System.out.println(input + " Celsius is " + result + " Fahrenheit"); } } } import java.util.; public class TempConversion { public static void main(String[] args) { double result; String degree; int input; degree = JOptionPane.showInputDialog("Enter: \n C - Fahrenheit to Celsius\n F - Celsius to Fahrenheit"); input = new Integer(JOptionPane.showInputDialog("Enter the degree:")).intValue(); if(degree == "C" \|\| degree == "c") { result = 5.0/9.0 (input - 32); System.out.println(input + " Fahrenheit is " + result + " Celsius"); } else if(degree == "F" \|\| degree == "f") { result = 9.0/5.0 * input + 32; System.out.println(input + " Celsius is " + result + " Fahrenheit"); } } } __________________ (Toggle Plain Text) countdown++; countdown++;

Jun 9th, 2005, 10:05 AM	#10
Knight Newbie Join Date: Jun 2005 Posts: 28 Rep Power: 0	The only reason I could think of why they have (2) variables is that, if you want to use the degreeF later on and you initially converted to degreeC, you just have to use the degreeF variable (which means you don't have to reconvert it again). So, I would stick this in the beginning: (Toggle Plain Text) // if they input it in farenheit first degreesC = 5.0/9.0 * (input - 32); degreesF = input; //if they input it in celsius first degreesF = 9.0/5.0 * input + 32; degreesC = input; // if they input it in farenheit first degreesC = 5.0/9.0 * (input - 32); degreesF = input; //if they input it in celsius first degreesF = 9.0/5.0 * input + 32; degreesC = input; That way, if you need the temperature in Farenheit, you could just use the variable degreesF and vice versa

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Jun 9th, 2005, 9:09 AM	#2
shangnyun Programmer Join Date: Jun 2005 Posts: 34 Rep Power: 0	I don't understand why it says "in a loop, prompt the user to enter a temperature (as an integer)"... isn't what I've come up with above perfectly sufficient for this first user-input?

Jun 9th, 2005, 9:15 AM	#3
Knight Newbie Join Date: Jun 2005 Posts: 28 Rep Power: 0	You have no loops in your code. That is your first problem. There are different types of loops, i.e. for while do-while etc... Try those and see what you come up with.

Jun 9th, 2005, 9:18 AM	#4
shangnyun Programmer Join Date: Jun 2005 Posts: 34 Rep Power: 0	Working on it. I just don't understand why I'm supposed to use a loop just so the user can enter an integer..

Jun 9th, 2005, 9:24 AM	#7
shangnyun Programmer Join Date: Jun 2005 Posts: 34 Rep Power: 0	No.. we are not doing Swing at all. But thanks.. that helped somewhat

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Programming Forums > Application Development > Java

Temperature Conversion Program - Help!