Directions for Lab #3

     5
C = --- (F - 32)
     9
    
     9
F = --- C + 32
     5

     5               5
C = --- (77 - 32) = --- (45) = 25
     9               9

     9
F = --- (25) + 32 = 45 + 32 = 77
     5

Individual steps:

1. The "assignment statement" below is not written in correct C++ syntax. Write the assignment statment on paper, using proper C++ syntax, in a manner that will cause the division operation to be performed first:

   
        5
   C = --- (F - 32)
        9
   

2. Using C++ integer division, what is the value of 5/9?
   
   
3. In view of your answer to step 2, what can you conclude about the assignment statement you constructed in step 1? What value does it assign to the variable C?
   
   
4. To reduce the error caused by integer division, rearrange the expression on the right hand side of the assignment operator so that the multiplication of 5 times (F - 32) occurs before division by 9.
   
   
5. Make a file called lab03.cpp from the skeleton program you see when you click here.
   
   
6. The purpose of program lab03.cpp is to read an integer Fahrenheit temperature and to calculate an integer estimate of the equivalent Celsius temperature. Fill in the body of function F_to_C() with C++ code to make it do the correct thing. Use the idea from step 4. Remember you need a return statement at the end of F_to_C(). Without the return statement, F_to_C() cannot give its result to its caller.
   
   
7. Test program lab03.cpp by running it several times, giving it a different input each time, and checking the answers it gives either with an electronic calculator or with hand calculations.
   
   
8. Think about how you would write this assignment statement in proper C++ syntax, and also to minimize the error caused by integer division:

   
        9
   F = --- C + 32
        5
   

9. Add to the program lab03.cpp a prototype and definition for a function C_to_F() that inputs an integer parameter Celsius and returns an integer estimate of the equivalent Fahrenheit temperature. Base the code in the body of this function on the C++ assignment you worked up in step 8. What hints do you have about where to put the new prototype and the new function definition?
   
   
10. Add statements in main() to prompt for and read an integer Celsius temperature, call C_to_F() to estimate a Fahrenheit equivalent, and print the Fahrenheit temperature. As a guide, use the existing statements that convert from Fahrenheit to Celsius. You can just copy those statements and then make the required changes to transform it into code that converts from Celsius to Fahrenheit.
    
    
11. As you did in step 7, test the program now with several values and check the results.
    
    
12. When you are sure everything is working correctly, make a script showing the program working on all the input values of step 11.
    
    
13. E-mail me a copy of the program source code (your completed file lab03.cpp) with subject line:
    
    CS1500Lab03Source
    
    E-mail me a (filtered) copy of the script with subject line:
    
    CS1500Lab03Script
    
    (A word about the subject lines - it is really extremely important that you use the exact subject lines I specify. This will assure that I am able to find your message among the hundreds and hundreds that I receive each day. You will lose a significant amount of credit for this assignment if you don't use the correct subject line. The easiest way to make sure you are using the correct subject line is to just select, copy, and paste it into the appropriate location when you are composing the e-mail.)
    
    You may refer to the directions of the "Hello World!" assignment if you need help with sending the e-mail. Also feel free to just ask someone - including me.