CPS 006, Lab4 Inlab

First you'll need to create a directory and copy some files into it. For the prelab you should have created a subdirectory lab4 in your cps006 directory. If you didn't do this, make sure you do it now:

Do these five commands only if you didn't complete the prelab

 cd
 cd cps006
 mkdir lab4
 cd lab4
 cp ~ola/cps006/lab4/* .

   cd
   cd cps006/lab4
   pwd                  (make sure it's your lab4 directory)
   mkdir inlab
   cd inlab
   cp ~ola/cps006/lab4/inlab/* .

If you type the ls command you'll find three files

• Makefile
• drawtriangle.cpp
• slots.cpp

RTP and Love

   make drawtriangle

Then run the program twice entering 5 and 20 for the number of rows.

You should notice that for 5 stars the program printed a diagram like this:

*
* * 
* * * 
* * * * 
* * * * * 

Now, remove the comment marker// before the call to PrintSpaces and recompile the program. The for loop in PrintTriangle should look like

Before you run the program you should try to figure out how the diagram will change. This will be good practice for test questions.

Run the program and work hard to understand why and how the output changed.

More General

Add this function to drawtriangle.cpp and then replace calls to PrintSpaces and PrintStars with calls to PrintStrings. The program should print the same shaped-triangle it did before you made the changes, i.e., the triangle whose top vertex is centered in the screen.

After making sure that PrintStrings works, modify the program so that the triangle is shaped as shown in the row below.

prompt> drawtriangle
how many rows: 10
                                                                            * 
                                                                          * * 
                                                                        * * * 
                                                                      * * * * 
                                                                    * * * * * 
                                                                  * * * * * * 
                                                                * * * * * * * 
                                                              * * * * * * * * 
                                                            * * * * * * * * * 
                                                          * * * * * * * * * * 

You should be able to make this change by changing just the number of spaces printed before stars are printed in each row, i.e., by changing MIDDLE-k to some other expression.

As a hint, there are 78 spaces printed before the star in the first row, 76 spaces printed before the first star in the second row, 74 before the first star in the third row, and so on.

As long as the triangle has a "flat" right edge, it doesn't matter where the edge is located.

Make sure a TA sees your working drawtriangle program with the function PrintStrings.

One-armed men and bandits

The current version simulates a kind of slot machine by showing three random strings on a line, and showing seven lines each time the program is run.

You are to make three modifications to the program.

1. First implement the functions whose prototypes follow.

   bool AllSame(string a, string b, string c)
   // post: return true if all strings are the same
   //       otherwise returns false
   
   
   bool AllDifferent(string a, string b, string c)
   // post: return true if all strings are different
   //       otherwise returns false
   
   

   For example, if there only two strings, the function AllSame could be written as follows.

    bool AllSame(string a, string b)
    // post: returns true iff a and b are the same
    {
        return a == b;
    }
   

   You'll want to use either the and operator && or the or operator || in writing these two functions.

   n You can ask the person near you for help if the TAs seem busy.

2. Now modify DoSlots so that after printing the simulated slot rolls (in the program there are seven lines printed) a message is printed as to whether the player is a winner or a loser. If the last three strings printed are all the same or are all different, the player is a winner. Otherwise the player is a loser. For example:

   prompt> slots
   orange orange orange
   cherry lemon orange
   lemon orange orange
   cherry cherry cherry
   lemon lemon cherry
   lemon cherry lime
   orange orange cherry
   
   a loser
   
   prompt> slots
   lemon cherry orange
   lemon orange orange
   lime orange lemon
   lemon orange lemon
   cherry cherry cherry
   cherry lime cherry
   orange cherry lime
   
   a winner 
   
   

3. Now modify the function DoSlots by first commenting out the coutstatements that print the random strings so that nothing is printed in the loop when the function executes. Then change the function from void to bool and instead of printing if the user is a winner or loser, return true if the user is a winner (the last strings "rolled" are all the same or all different) and return false if the user is a loser.

   Now call DoSlots(7) 10,000 times from main (write a loop) and accumulate a count of how many times the user wins. Print this result. Here's a start at the code in main, it's not complete.

       int count=0;
       for(int k=0; k < 10000; k++)
       {
   	if (DoSlots(7)) 
           {
   
           }
       }
   

   write percentage here _______________

Be sure to call the TA over to check your program.

Finishing

  submit_cps006 lab4 *.cpp