Lab03 Temperature Converter with Ifs

1. Quick introduction to the if statement (lab begins at step 2): Consider the following code which tells you whether you need to take a raincoat or not.

On a “Yes” entered:

On a “No” or anything but a “Yes”, entered:

Note:

a. The general structure of:

if(/*test*/)}

{

/*if logic*/

}

else{

/*else logic*/

}

b. The way this works, as you might suspect, is that the test in parentheses after the if evaluates to a true or false value. If the test passes, then we do the if logic, otherwise we do the else logic, mutually exclusively.

c. The test, ans.equals("Yes") compares the answer to the String "Yes", if they are character for character identical, then it returns true, otherwise false.

d. There are other versions of the if statement, one without the else, and many with more cases, but this basic structure is fine for this lab.

e. The else happens if the if's condition evaluates to false.

f. This is one of the most important programming features in Java, indeed in many of the related languages, because it is generally useful.

2. Now write a program that will convert:

a. First, let’s see the intended input and output:

b. Asks the user for the temperature, a number. Store it in a double variable, e.g.
double temp=keyboard.nextDouble();

i. double is the type. We've used int, which is, of course, short for integer.

ii. keyboard is a Scanner

iii. doubles are just another type of value we can use; they store floating point numbers (numbers that can represent numbers with a decimal or radix point)

c. IMPORTANT: After the previous step, call keyboard.nextLine(), where keyboard is the Scanner, to clear the input. nextDouble() only reads the line until it has a number, and no more. There will be some stuff left over that needs be cleared. We do not store the value returned from the line in a variable since we do not need it, i.e.,just:

keyboard.nextLine();

d. The program then asks the user for the unit ,"C" or "F" (Celsius or Fahrenheit).

e. Then, use the unit to determine whether it's converting Celsius to Fahrenheit or Fahrenheit to Celsius. Use the following formulas, where T_c and T_f are temperatures in Celsius and Fahreheit, respectively.

i. T_f=(9.0/5.0)*T_c+32.0

ii. T_c=(5.0/9.0)*(T_f-32.0)

iii. PITFALL: You need to include the “.0” after the numbers, otherwise the result of (5/9) will be 1 (integer division in Java returns an integer, which is rounded down here).

f. Now, test your program. Suggested tests(test both directions, C<->F):

i. 0C is 32F

ii. 100C is 212F

g. Try to get the unit for the result on the same line as the converted number.

i. System.out.println() always adds a new line after printing the input argument.

ii. System.out.print() won't add the new line automatically.

3. Upload your code and make sure you have signed the roll.