Directions for Lab #5

Individual steps:

1. Make a file called lab05.cpp from the program skeleton you see when you click here.
   
   
2. Read the program. Pay special attention to the comments under the function declarations near the top of the program file. The comments explain what the functions are supposed to do.
   
   
3. In the main function, add the needed C++ instructions under each of these comments:
   
   
   • // Call function PrintInfo.
     
     
   • // Call function GetScore, to obtain a value for score1.
     (Hint: write an assignment statement with score1
     on the left and a call to GetScore() on the right.)
     
     
   • // If score1 is out of range, print an error message.
     (Use a call to function RangeError to test score1,
     not inline code. The message should tell the user
     that s/he entered an incorrect score and s/he will need to
     start over by running the program again.)
     
     
   • // else
     • Call GetScore a second time, to obtain a value for score2.
       (Use another assignment statement - with score2
       on the left and a call to GetScore() on the right.)
       
       
     • // If score2 is out of range, print an error message.
       (This message could be almost the same as the one the
       program prints if score1 is out of range.)
       
       
     • // else, using a call to function maximum() within a cout
       // statement, print the maximum score.
       (Hint: The call to maximum() is an expression that
       returns the maximum of the two scores, but maximum()
       does not write to the screen. A cout in main will be
       required here.)
       
       
   
   Be careful to group the statements in the first else clause with braces to form a compound statement (aka a block). The first else clause is the outer else clause. It has an if-else statement nested inside it. Remember that you have to write the logic of the program so that any time the user enters an invalid score, the program will immediately print an error message and stop.
   
   Use your understanding of what each function is supposed to do to guide you as you write the function calls in this part of the program. (Important: Make sure to first read and understand all the comments under the function declarations (aka prototypes). The functions must do exactly what the comments say the functions do -- nothing less, and nothing more. Be guided by this when you write the part of the program that uses the functions.)
   
   After you complete this step, raise your hand and ask me to check your work.
   
   
4. In the next several steps you will put stub code (placeholder code) into the level-two functions (the functions that are called by the main function). After you do this, the program will still be unfinished. However, you will be able to compile and execute the program. You will be able to check to see if main is performing correctly (the main function of the program).
   
   Through the use of stubs, a programmer can build and test a program one function at a time. This is a very valuable technique. It keeps things pretty simple for the programmer, even when the program is very large and complex.
   
   
5. Under the comment in the body of function GetScore write the following stub code:

        cout << "Entering function GetScore" << endl ;
        return 300 ; 

6. Under the comment in the body of function RangeError write the following stub code:

        cout << "Entering function RangeError" << endl ;
        return false ; 

   The return value of false means that the score (300) is OK - it is within the correct range.
   
   
7. Under the comment in the body of function maximum write the following stub code:

        cout << "Entering function maximum" << endl ;
        return x ; 

8. Compile and execute the program. Debug the program before continuing. The output should have a structure like this example:

   This program interactively reads two quiz
   scores and prints the maximum.
   
   Entering function GetScore
   Entering function RangeError
   Entering function GetScore
   Entering function RangeError
   The maximum of the two scores is: Entering function maximum
   300
   

   In other words, you should first see two sets of outputs from the stub GetScore and stub RangeError functions, and then output from the stub maximum function. The output from the stub maximum function will probably be sandwiched between output from a cout in main, the cout that tells what the maximum is.
   
   After you have verified that the program produces output like this, send me a copy of the source code by e-mail. Use the subject line: CS1500_Lab5_Vers1
   
   
9. Change the stub code in function GetScore so that it returns 950 instead of 300. Change the stub code in function RangeError so that it returns true instead of false, which means that the score (950) is NOT within the correct range. Then compile and execute the program. Now the output should have a structure like this example:

   This program interactively reads two quiz
   scores and prints the maximum.
   
   Entering function GetScore
   Entering function RangeError
   You entered an invalid score.
   Scores must be in the range 0-800 (inclusive).
   Please try again.

   (In other words, you should see exactly one output from GetScore, one from RangeError, and then an error message about invalid data. If you see more than one output from GetScore and RangeError then probably either you forgot to put the first else keyword in your program, or you forgot to enclose between braces the statements after the first else. Whatever the error(s), figure out what's wrong, and fix it.)
   
   When you have the program producing output like the example above, send me a copy of the source code by e-mail. Use the subject line: CS1500_Lab5_Vers2
   
   
10. Change the stub code in function RangeError so that it returns false (as before). Then delete the stub code from inside GetScore and put code inside it that makes it do what it is supposed to do, as a finished product.
    
    The comment below the declaration of function GetScore says:

    "Prompt for a score (an int), read it & return it."

    Therefore you write the code to make GetScore do exactly that - no more or less.
    
    The code in GetScore should declare a (local) int variable, write a prompt for the user, input a number into the local variable, and then return the variable. If you want to see an example of the type of function I mean, look at the function GetDim in this program.
    
    Compile and execute the program (lab05.cpp). Debug the program before continuing. If you run the program and enter scores of 250 and 340, the output should have a structure like this example:

    This program interactively reads two quiz
    scores and prints the maximum.
    
    Enter a quiz score: 250
    Entering function RangeError
    Enter a quiz score: 340
    Entering function RangeError
    Entering function maximum
    The maximum of the two scores is: Entering function maximum
    250
    

11. Replace the stub body of RangeError with code that makes it work correctly (i.e. replace its stub code with code that makes RangeError do what the comment below the declaration of RangeError says it should do - no more and no less). You can do this with one line of code: a return followed by a Boolean expression. You can also use if-(then)-else logic that selects between two different return statements.
    
    
12. Similarly, replace the stub body of function maximum with code that makes it do just what the comment below its declaration says it should do. (Note: function maximum is not supposed to write to the screen.) Try writing the code this way: first declare a temporary variable; second, use if-(then)-else logic to do both these things: test which parameter is the max, and store the max in the temporary variable; finally, return the value of the temporary variable. Make sure that your function returns a correct result in all cases: x less than y, x greater than y, or x equal to y.
    
    
13. Compile and test the program by running it five times on different kinds of inputs:
    
    
    • The first score entered is out of range.
    • The first score entered is in range, but the second is not.
    • Both scores are in range and the first score is larger than the second.
    • Both scores are in range and the second score is larger than the first.
    • Both scores are in range and the scores are equal.
    
    
14. Debug and re-test as necessary. When the program is working correctly on all five types of input, make a single script that shows all five tests. E-mail me a copy of the final version of the program source code with subject line: CS1500_Lab5_Fin and e-mail me a copy of the (filtered) script with subject line: CS1500_Lab5_Scr
    
    As usual, you can refer to the Hello World! example for details on how to make and filter a script file, and on how to e-mail files to me.