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 of 5 by 9 to be performed before the multiplication by (F - 32):

   
        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 right hand side (RHS) of the assignment statement with a C++ expression that will make the assigment statement do the correct thing. Use the idea from step 4. Use only int variables and constants. (No constants with decimal points or variables of type double or float.)
   
   
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. Now think about how you would write the assignment statement below in proper C++ syntax. Think about how to do it in a way that will minimize the error caused by integer division:

   
        9
   F = --- C + 32
        5
   

9. At the end of main(), but before the return statement, add statements that do the following things (in the same order listed below):
   
   
   • prompt for an integer Celsius temperature,
   • read the integer into the variable named Celsius,
   • assign to the variable Fahrenheit the Fahrenheit temperature corresponding to the Celsius temperature stored in the variable Celsius, and
   • print the Fahrenheit temperature.
   
   Base the assignment on what you worked up in step 8. In this assignment statement too, there must be only int variables and constants. (No constants with decimal points or variables of type double or float.)
   
   
10. As you did in step 7, test the program now with several values and check the results.
    
    
11. When you are sure everything is working correctly, make a script showing the program working on all the input values of step 10. (When you make the script, you'll have to run the program several times -- so that you can test several sets of inputs.) Remember to clean up the script using the filtering technique you learned.
    
    
12. E-mail me a copy of the program source code (your completed file lab03.cpp) with subject line:
    
    CS1500Lab03Source
    
    E-mail me a copy of the filtered script with subject line:
    
    CS1500Lab03Script
    
    (A word about the subject lines - it is very important that you use the exact subject lines I specify. This will assure that I am able to find your message among the many 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.