Multi Dimensional Arrays

Much of the data computers process is stored in the form of tables.

Hours worked/week
Employee #	Week 1	Week 2	Week 3	Week 4
1	10	10	15	15
2	25	27	26	28
3	30	30	30	30
4	40	45	42	41
5	40	35	35	35

Tables have rows and columns. Columns are vertically arranged data, and rows are horizontally arranged data.

How can we represent the data in the table in C++?

We can use 5 different arrays, but do we arrange these by Employee or by week?

C++ allows us to represent table data as a two dimensional array. The rows and columns have a matrix structure.

column row	0	1	2	3
0	0,0 10	0,1 10	0,2 15	0,3 15
1	1,0 25	1,1 27	1,2 26	1,3 28
2	2,0 30	2,1 30	2,2 30	2,3 30
3	3,0 40	3,1 45	3,2 42	3,3 41
4	4,0 40	4,1 35	4,2 35	4,3 35

To declare a 2 dimensional array for the table:

int hoursperweek [5][4];

Alternately:

int rows = 5;

int columns = 4;

int hoursperweek [rows][columns];

In general:

datatype arrayname [numberrows][numbercolumns];

We can initialize two dimensional arrays in the declaration.

char ticTacToeBoard[3][3] = {{'x', 'x', 'o'},

{'o', 'o', 'x'},

{'x', 'o', ' '}

};

int A[3][4] = {8, 2, 6, 5}, //row 0
  6, 3, 1 ,0, //row 1
  8, 7, 9, 6}; //row 2

Problem: The employee table is stored in a file.

1. Read the values into a 2 dimensional array

2. Print:

a. The average hours worked per week

b. The average number of hours worked per employee

Three dimensional arrays

const int rows = 3;

const int columns = 4;

const int rank = 2;

int dim3 [rows][columns][rank]

Need 3 loops to process a three dimensional array.

Need n loops to process an n dimensional array.