1 / 17

# Multidimensional Arrays - PowerPoint PPT Presentation

Multidimensional Arrays. Chapter 13. The plural of mon goose starts with a "p". Initializing a multidimensional array. 0 1 2 3 4. Processing by row. 0 1 2 3. Printing the contents of an array. Processing by column. Two dimensional Arrays.

Related searches for Multidimensional Arrays

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Multidimensional Arrays' - Philip

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Multidimensional Arrays

Chapter 13

The plural of mongoose starts with a "p"

Initializing a multidimensionalarray

0 1 2 3 4

Processingby row

0

1

2

3

Printing thecontents ofan array

Processingby column

• A collection of components

• all of the same type

• structured in TWO dimensions

• each component accessed by a PAIR of indices representing the component’s position in each dimension

0 1 2 3 4

0

1

2

3

Which cell isLocation (2,3) ?

0 1 2 3 4

0

1

2

3

• Syntax: data_type array_name [row_dim][col_dim];

• Example:

• First element isint_table[0][0]

• Last element isint_table[4][3]

int int_table [5][4];

• Arrays processed in some pattern

• random

• along rows

• along columns

• whole array

• We will use the declaration shown below:

int int_table [5][4];int row, col;

• What does the routine below do with the array? What should we name the function?

total_a_row

0

• What does this routine below do with the array? What should we name the function?

total_column

0

• This function initializes an array.

• Fill in the blanks with the correct identifiers

3

col

table

value

row

row

row

col

col

col

• We must process each row, item by item

• Which will be the inner loop?Which will be the outer loop?

• The LCV of the inner loop must be the one which changes the most often

What goeshere?

endl

• Recall declaration for 1-D array

• we didn’t specify the size in the brackets

• we sent the size as a separate parameter

• Recall name of the array is a pointer constant

• tells where the array starts in memory

• this is what is passed to the function

void whatever ( float num_list [ ], int size);

• For a 2-D array, declare

• We are sending the starting address

• also how many elements it takes to jump us to the next row

• that is -- the number of columns

• Note that this could be for an array for ANY number of rows, but exactly 4 columns

• As with 1-D, we also send another parameter for the function as a limiting value

void whatever ( float num_table [ ][4], int num_rows);

• Think of the 2-D array as an array of arrays

• Example

• Each element of renters is an array of rent_pmts

typedef float rent_pmts [12];rent_pmts renters [6];

0 1 … 10 11

0

1

5

• C++ arrays not limited to two dimensions

• limitation is amount of memory

const int NUM_BLDGS = 10;const int APTS_PER_BLDG = 12;float apt_pmts [NUM_BLDGS][6][APTS_PER_BLDG];

• C++ arrays not limited to two dimensions

• limitation is amount of memory

const int NUM_BLDGS = 10;const int APTS_PER_BLDG = 12;float apt_pmts [NUM_BLDGS][6][APTS_PER_BLDG];

This gives a 3-D array with 720 itemsapt_pmt [bldg][tennant][apt]

• Initialize all components of an array

• Use the same number of indeces as the declaration of array

• Make sure indeces are in order

• don’t reverse row and column references

• Use meaningful identifiers for the array name and indeces

• Double check upper and lower bounds on indeces

• don’t walk off the edge of the array

• When declaring multidimensional array as a formal parameter

• must state sizes of all but first dimension

• When calling function with array as parameter

• sizes of multi-dim actual parameter must match exactly sizes of formal

• Use typedef statement to define multi-dimensional array type

• use this for actual and formal parameter declaration