Project FAQ

MACS 261 Final Project Frequently Asked Questions

How do I generate random behavior in my program?

C includes a random number generation function called rand() which returns a random number from 0 to (MAXINT - 1). For example:

int num;

num = rand();

assigns a random value to num. To limit the range of numbers, use the modulo function:

num = rand() % 100;

assigns a number from 0 to 99 to num.

To have different number sequences each time you run your program, you need to use a function called srand:

srand((unsigned int) time(0));

This function call should included just once in your program, BEFORE your first call to rand().

To use these functions, you must include the libraries:

#include <stdlib.h>

#include <time.h>

How can I time some behavior in my program?

The time(0) function used to generate a seed for srand (in the above example) actually returns a representation of the current time. If you call that function once before your behavior and again after the behavior, you can subtract the two to find out the number of seconds of execution.

How can I allow the user to enter the file name?

The file name parameter to the open function is just a character array (string). You may use a variable rather than a literal string. For example:

ifstream fin;

char filename[16];

cout << "Enter file name: ";

cin >> filename;

fin.open(filename);

How can I represent a deck of cards?

There are several ways to represent a deck of cards. The first issue is how to represent the value of 1 card. Assume you have the following declarations (can be global, should not be part of a class):

const char suits[4][9] = {"Hearts","Diamonds","Clubs","Spades"};

const char faces[13][6] = {"Ace","Deuce","Three","Four","Five","Six",

"Seven","Eight","Nine","Ten","Jack","Queen","King"};

Then the value for a card might be represented as a pair of numbers, one value from 0-3 which represents the suit, one value from 0-12 which represents the face value. For example, the value of 0 for suit and 0 for face represents the Ace of Hearts. Value of 0 for suit and 1 for face represents the Deuce of Hearts, and so on. (If this isn't clear, draw the two declarations above as an array, including indices. Notice that suits[0] contains Hearts and faces[0] contains Ace, etc.).

So how would you represent an individual card? Although you might use a 2D array for this purpose (related to the two dimensions of suit and face), you can also use a single value in the range of 0-51. The algorithm to convert from a card's numeric value to the card representation is:

suit = card_value/13;

face = cards_value%13;

For example, if the card_value is 10, 10/13 = 0 so the suit is Hearts, 10%13 = 10 so the face is Jack. If the card_value is 14, 14/13 = 1 so the suit is Diamonds, 14 % 13 = 1.

A deck of cards would be just an array of 52 of these card values. For example:
Index Card
0          0
1          1
2          2
3          3
4          4
5          5
6          6
7          7
8          8
9          9
10      10
....
would be a deck of cards that are sorted.

To shuffle, take each card in order and randomly swap it with one other card in the deck (see rand() function above). The result would be something like:
Index    Card
0         14
1         23
2           8
3         45
4         21
5          0
6         37
7         32
8         10
9         41
10       51
...

In this example, the top card in the deck is now the Jack of Hearts.

To deal, you need an integer that keeps track of the next card to be dealt, and arrays of integers that represent the players' hands. For example, to deal two cards to two players from the above shuffled deck, you would have

Player1 Player2
14 23
8 45

You may want to put the hands in a 2D array, so that each player can be represented by a player number.

Additional information will be added to this document as questions arise.