Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

Programming with Two-Dimensional Arrays: Notations, Declaration, and Applications, Slides of Computer Science

Biju Patnaik University of TechnologyComputer Science

A lecture note from a computer science 106 or computing in engineering and science course, dated may 9, 2006. It discusses the concepts of two-dimensional arrays, their notations, declarations, and applications. The document also covers passing two-dimensional arrays to functions and higher-dimensional arrays. It includes examples and exercises.

Typology: Slides

2013/2014

Uploaded on 02/01/2014

savitri_122
savitri_122 🇮🇳

4.6

(14)

184 documents

1 / 6

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Programming with two-dimensional arrays May 9, 2006
1
Programming with Two
Programming with Two-
-
dimensional Arrays
dimensional Arrays
Larry Caretto
Computer Science 106
Computing in Engineering
and Science
May 9, 2006
2
Outline
• Review basics of 2D arrays
– Contrast with 1D arrays
– Notation and declaring array sizes
• Code applications with 2D arrays
• Passing 2D arrays to functions
• Higher-dimensional arrays
• Summary of array use
3
Two-dimensional Arrays
• One-dimensional arrays refer to a
variable that has multiple entries with a
single classification
• Two-dimensional arrays are used to
represent data with two classifications
– Example: an experiment on manufacturing
productivity measures daily output of four
machines with six operators
4
Two-dimensional Arrays
• One-dimensional variable
– mathematical notation xi
– C++ array notation x[i]
• Two-dimensional
– mathematical notation xik
– C++ array notation x[i][k]
• One-way versus two-way classification
5
Two-Dimensional Array
[6][4]
[5][4]
[4][4]
[3][4]
[2][4]
[1][4]
[0][4]
[6][3]
[5][3]
[4][3]
[3][3]
[2][3]
[1][3]
[0][3]
[6][2]
[5][2]
[4][2]
[3][2]
[2][2]
[1][2]
[0][2]
[6][1]
[5][1]
[4][1]
[3][1]
[2][1]
[1][1]
[0][1]
[6][0]
[5][0]
[4][0]
[3][0]
[2][0]
[1][0]
[0][0]• View two-
dimensional
arrays as a
table with
rows and
columns of
cells
•Row index
• Column
6
Two-dimensional Example
• In the example of a manufacturing
process measuring the output of four
machines with six operators
– Array named output depending on integer
subscripts machine and operator
– First subscript is for operator and second is
for machine
const int maxOp = 6, maxMach = 4;
int output[maxOp][maxMach];
cout << output[3][2];
pf3
pf4
pf5

Partial preview of the text

Download Programming with Two-Dimensional Arrays: Notations, Declaration, and Applications and more Slides Computer Science in PDF only on Docsity!

Programming with Two-Programming with Two-

dimensional Arraysdimensional Arrays

Larry Caretto Computer Science 106

Computing in Engineering

and Science

May 9, 2006

2

Outline

  • Review basics of 2D arrays
    • Contrast with 1D arrays
    • Notation and declaring array sizes
  • Code applications with 2D arrays
  • Passing 2D arrays to functions
  • Higher-dimensional arrays
  • Summary of array use

3

Two-dimensional Arrays

  • One-dimensional arrays refer to a

variable that has multiple entries with a

single classification

  • Two-dimensional arrays are used to

represent data with two classifications

  • Example: an experiment on manufacturing productivity measures daily output of four machines with six operators

4

Two-dimensional Arrays

  • One-dimensional variable
    • mathematical notation xi
    • C++ array notation x[i]
  • Two-dimensional
    • mathematical notation xik
    • C++ array notation x[i][k]
  • One-way versus two-way classification

5

Two-Dimensional Array

[6][4]

[5][4]

[4][4]

[3][4]

[2][4]

[1][4]

[0][4]

[6][3]

[5][3]

[4][3]

[3][3]

[2][3]

[1][3]

[0][3]

[6][2]

[5][2]

[4][2]

[3][2]

[2][2]

[1][2]

[0][2]

[6][1]

[5][1]

[4][1]

[3][1]

[2][1]

[1][1]

[0][1]

[6][0]

[5][0]

[4][0]

[3][0]

[2][0]

[1][0]

[0][0] • View two-

dimensional

arrays as a

table with

rows and

columns of

cells

  • Row index
  • Column 6

Two-dimensional Example

  • In the example of a manufacturing

process measuring the output of four

machines with six operators

  • Array named output depending on integer subscripts machine and operator
  • First subscript is for operator and second is for machine const int maxOp = 6, maxMach = 4; int output[maxOp][maxMach]; cout << output[3][2];

7

Two-Dimensional Array Data

M tot 208 316 265 202 991

Op tot

M 3

M 2

M 1

M 0

Op 5

Op 4

Op 3

Op 2

Op 1

Op 0

Individual

data plus

totals for

operators

and

machines

output[3][2]

Array data 8

Two-dimensional array Code

const int maxOp = 6, maxMach = 4

int output[maxOp][maxMach];

for (int op = 0; op < maxOp; op++)

for ( int mach = 0; mach <

maxMach; mach++ )

cout << output[op] [mach] <<

“ units produced at machine “

<< mach << “ with operator “

<< op;

9

Other Code

  • How would you compute the total units

produced by each machine?

  • How would you compute the total units

produced by each operator?

  • How would you compute the average

and standard deviation for all the units

produced by the operators?

10

Units for Each Machine

  • This sum is the total output of each machine

from all operators (column sum)

int outMach[maxMach]; for (int mac = 0; mac < maxMach; mac++) { outMach[mac] = 0; for (int op = 0; op < maxOp; op++) {outMach[mac] += output[op][mac];} cout << “Total machine “ << mac << << “ output is “<<outMach[mac]; }

11

Units for Each Operator

  • This sum is the total output of each

operator from all machines (row sum)

int outOp[maxOp]; for ( int op = 0; op < maxOp; op++ ) { outOp[op] = 0; for ( int m = 0; m < maxMach; m++ ) { outOp[op] += output[op][m]; } cout << “Total operator “ << op << “ output is “ << outOp[op]; } 12

Comments on this Code

  • Note that we use one-dimensional

arrays to store row (operator) and

column (machine) sums

  • Note that order of subscripts is always

[operator][machine]

  • Conventional, but not required, to write

tables as arrays with subscript ordered

as [row][column]

19

Passing 2D Arrays to Functions II

  • Consider an array x with declared as

x[totalFirst][totalSecond]

  • The location of x[i][j] is computed as i +

j*totalSecond locations from the start of

the array

  • We must know the second dimension to

compute the location

  • We must pass this second dimension to

the function that has a two-dimensional

array as a parameter

20

Passing 2D Arrays to Functions III

  • Global constant: const int maxSecond = 20
  • Function header double getSum ( double x[][maxSecond],…
  • Function prototype (semicolon at end) double getSum ( double x[][maxSecond],… double getSum ( double [][maxSecond],…
  • Calling program const int maxFirst = 20; double x[maxFirst][maxSecond]; // other code assigns values to x array double result = getSum( x, ….

21

Passing 2D Arrays to Functions IV

  • Global constant not required, but helpful

to accommodate changes to size of

second dimension

  • The second dimension must be the same

in the following three statements:

  • The function prototype
  • The function header
  • The declaration of the array passed to the function
  • Final project uses two-dimensional arrays 22

Passing 2D Arrays to Functions V

  • Example: write a function that accepts a

two-dimensional array, output, used in

the previous example and computes and

returns the row sums and columns sums

as well as the total

  • How to pass information?
    • Pass 2D output array into function
    • Return 1D arrays with row and column sums
    • Return total in function name
    • Pass number of machines and operators, which can be less than the maximum array sizes, into function

23

Example of 2D Array Function

int getSums( int output[][maxMach], int opSum[], int machSum[], int Nop, int Nmach) { int total = 0; for ( int op = 0; op < Nop; op++ ) { opSum[op] = 0; for ( int m = 0; m < Nmach; m++ ) opSum[op] += output[op][m];

total += opSum[op]; } // continues on next chart 24

2D Array Function Concluded

for ( int m = 0; m < Nmach; m++ ) { machSum[m] = 0; for ( int op = 0; op < Nop; op++ ) machSum[op] += output[op][m]; } return total; } // closes function opening brace

  • How do we use this function?
  • What is its prototype?

25

Using the 2D Array Function

  • Start with global constants for common

array dimensions in various locations

const int maxMach = 10, maxOp = 10;

  • Prototype is just header with a semicolon int getSums( int output[][maxMach], int opSum[], int machSum[], int Nop, int Nmach);
  • Use global constants as array dimensions in

calling program

int output[maxOp][maxMach], opSum[maxOp], machSum[maxMach]; 26

Using the 2D Array Function

  • Get data in calling program (usually from

file)

ifstream inFile( “production.dat” ); inFile >> Nop >> Nmach; for (op = 0; op < Nop; op++ ) for ( m = 0; m < Nmach; m++ ) infile >> output[op][m];

  • Call function int total = getSums( output, opSum, machSum, Nop, Nmach);
  • Output results

Array call has only

array names

27

Input Data Files for Arrays

  • Must match input statements in code for (i = 0; i < N; i++) inFil >> x[i]; for (i = 0; i < N; i++) inFil >> y[i];
  • Compare above statements with code below for (i = 0; i < N; i++) { inFil >> x[i] >> y[i]; }
  • First example read all x data then all y data.

Second reads x and y data in pairs

  • Usually write code to determine number of

array elements by testing for end of file

28

Input Data File for 1D Arrays

  • How does the code

below read x and y from

each file on this page?

for (i = 0; i < 3; i++) cin >> x[i] >> y[i];

  • What about this code? for (i = 0; i < 3; i++) cin >> x[i]; for (i = 0; i < 3; i++) cin >> y[i];

29

Input Data Files for 2D Arrays

  • Recall input code from example of passing

2D arrays to functions

ifstream inFile(“production.dat”); inFile >> Nop >> Nmach; for (op = 0; op < Nop; op++ ) { for ( m = 0; m < Nmach; m++ ) { inFile >> output[op][m]; } }

  • How would you prepare the data file?

Braces not needed 30

Input Data File for 2D Arrays

  • Usually prepare data file for 2D arrays

to look like row and column data