CSE1301 Computer Programming:

Lecture 27Game Programming: Bingo

Topics

• Problem Specification

• Top-down Design

• Structure Chart

• Random number generation

Reading: D&D: 5.9

Bingo: The Board • Cards have random numbers assigned to cells in the ranges

shown (each number can appear at most once only.)

• The central card is marked initially.

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The Game of Bingo

• The game master calls out numbers 1-75 randomly.

• The player places a marker on top of a number that is called if it is on the card.

• The winner is the first player whose card has a straight line (row, column or main diagonal) filled with markers.

Winning Positions

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Example Game

• Use 5x5 grid in your lecture notes

• "Randomly" fill in your card, with numbers from the correct ranges.

• Swap cards with your neighbour.

Bingo Program Requirements

• To play Bingo with ?? – N players and a game master (the program).

• Each player has ?? – a bingo card whose entries have been chosen

randomly.

• The game master (program) - does what???– calls out a number in the range 1-75 at random

Bingo Program Requirements • Each player - does what?

– covers a cells with a marker if it contains the number called by the game master;

– done by the program.

• The game ends when ??

– one player has markers covering all cells in a row, column, or main diagonal;

– checked by the program.

• At the end of the game ??

– The winner is announced.

– The prize is awarded

Main Task - Algorithm

fill N game boards randomly print out N game boards while no player has won yet { call out a random number update game boards for all players printout N game boards } announce winner

Main Task - Structure Chart

Data Structures - the Board

• How do we organise the board? – Hint: how will we access the board?

• Organise the board around columns and rows.

int board [5][5];

/*if cell value is 0, then it is marked*/

Printing a Board (algorithm)

FUNCTION print Board (board)

{

print header for each row

{

for each column { printcell for that row and column }

}

}

Printing a cell (code)

const int MARKED=0;

printcell(int cellValue)

{ if (cellValue == MARKED) { printf (" **") } else { printf ("%4d", cellValue); }

}

Creating the Board FUNCTION Create Board

{ for each column { generate 5 random numbers in range place them in that column } mark the cell at row 3 in column 3

}

Q. Anyone see a problem with this algorithm?

A. Random numbers must be unique.

FUNCTION Create Board

{ for each column

{ for each row from 1 to 5

{

generate a random number in range for that column while random number is a duplicate

{ generate another number } } place random number in the row }

mark the cell at row 3 in column 3

}

Checking for duplicates

• Use an integer array which server as flags:int numberFlags[75];

• All elements are initialised to 0.

• If a number i is chosen, flag the number as “used” by setting value of numberFlags[i-1] to 1.

Checking for duplicates

IsDuplicate (number, flags array)

{ if (content of flags array at position (number -1)

is equal to 1) { return true /* duplicate found */ } return false

}

Generating a random number

• Use C function rand (). • rand() generates an integer between 0

and RAND_MAX.

Generating a random number

int randomNumberInRange (int min, int max)

{ return (rand () % (max - min + 1) + min);

}

Example

column range 16-30 (min 16, max 30)

Suppose rand() returns 403

max - min + 1 = 15

403 % 15 = 13

13 + 16 = 29

int randomNumberInRange (int min, int max)

{ return (rand () % (max - min + 1) + min);

}

Data structure for players

• N players: an array with N elements. • What is each element to be?

struct playerRec { char name[NAMELENGTH]; int board[5][5]; };

typedef struct playerRec Player; Player players[N];

Unique Called Numbers

• How to ensure that the number has been called out at most once?

• A boolean array is a good solution.

int calledNumbers [75]; int i;

/* initialise all to false */ for (i=0; i<75; i++) { calledNumbers[i] = 0; }

Playing one round (algorithm)

playOneRound

{ generate a random number between 1 and MaxBingoInt

while the random number has already been called { generate a random number } mark the number as called

}

Updating board (algorithm) updateBoard (board, number)

{ for each row and column

{ if cell at row, column is equal to number

{ set cell to MARKED }

}

}

Summary

• First, analyse the problem - structure chart - data structures and actions on data

• Construct modules - main program loop : top-down - I/O: bottom up

• Bingo program available on the web: http://www.csse.monash.edu.au/courseware/cse1301