Difference between revisions of "C-and-C++/C3/Working-With-2D-Arrays/English"
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Revision as of 16:23, 18 December 2013
Title of script: Working with 2D arrays
Author: Ashwini Patil
Keywords: : 2D arrays, Matrix addition, video tutorial()
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Slide 1 | Welcome to the spoken-tutorial on 2dimensional Arrays in C and C++. | ||||||||||||
Slide 2 | In this tutorial we will learn,
What is an 2D array. We will do this with the help of an example. | ||||||||||||
Slide 3 | To record this tutorial, I am using
Ubuntu Operating System version 11.04, gcc and g++ Compiler version 4.6.1 on Ubuntu | ||||||||||||
Slide 4 | Let us start with the introduction to 2 dimensional Array
2-D arrays are stored in a row column matrix. The left index indicates the row. The right index indicates the column. 0 1 2 3
We can visualize a 2-D array in the form of a matrix. Matrix is composed of multiple rows and horizontal columns. Starting index of a matrix or array in C and C++ is always 0. | ||||||||||||
Slide 5 | Let us see how to declare 2 dimensional array
The Syntax for this is: data-type arr_name[row] [col]; eg. int num[2][3]; | ||||||||||||
On the editor | Now let us see how to declare an 2D array through an example.
I have already typed the program on the editor. So, I will open it. Let me explain the program. | ||||||||||||
Point to array.c | Note that our file name is 2d-array.c | ||||||||||||
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#include <stdio.h> |
This is our header file. | ||||||||||||
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int main() |
This is our main function. | ||||||||||||
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int i,j;
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Here, we have declared variable i and j. | ||||||||||||
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int num1[3][4],num2[3][4]; |
Here we have declared num1 with 3rows and 4columns
And num2 with 3rows and 4columns | ||||||||||||
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printf("Enter the elememts of 3X4 array num1\n"); for(i=0; i<3; i++) for(j=0; j<4; j++) scanf("%d", &num1[i][j]); |
Here we take elements of the matrix num1 as input from the user.
The elements are stored row-wise. We have considered i for rows. We have considered j for columns. This for loop will check the condition that i runs from 0 to 2. This for loop will check the condition that j runs from 0 to 3. | ||||||||||||
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printf("Enter the elememts of 3X4 array num2\n"); for(i=0; i<3; i++) for(j=0; j<4; j++) scanf("%d", &num2[i][j]); |
Here we take elements of the matrix num2 as input from the user.
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printf("The 3X4 array num1 is\n"); for(i=0; i<3; i++) { for(j=0; j<4; j++) printf("%3d ", num1[i][j]); printf("\n"); } |
Here we display the matrix num1 | ||||||||||||
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printf("The 3X4 array num2 is\n"); for(i=0; i<3; i++) { for(j=0; j<4; j++) printf("%3d ", num2[i][j]); printf("\n"); } |
Here we display the matrix num2 | ||||||||||||
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printf("The sum of num1 and num2 is\n"); for(i=0; i<3; i++) { for(j=0; j<4; j++) printf("%3d ", (num1[i][j] + num2[i][j])); printf("\n"); } |
Here, we add the num1 matrix and the num2 matrix
Then we display the result | ||||||||||||
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return 0; |
This is our return statement. | ||||||||||||
Click on Save | Now, click on Save. | ||||||||||||
Let us execute the program. | |||||||||||||
Press Ctrl, Alt and T keys | Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously. | ||||||||||||
On the terminal
Type gcc array.c -o arr ./arr |
To compile type,
gcc 2d-array.c -o 2darr To execute type, ./2darr | ||||||||||||
Now let us see how to execute the same program in C++. | |||||||||||||
On the editor | Come back to our program. | ||||||||||||
I will change a few things here. | |||||||||||||
Click on File menu
Click on Save as option |
First click on File menu,
Click on Save as option, Save the file with .cpp extension. | ||||||||||||
Type
iostream |
First lets change the header file as iostream | ||||||||||||
Type
using namespace std; |
Let us include the using statement. | ||||||||||||
Type
cout << |
Now replace the printf statement with the cout statement.
Here, \t mean horizontal tab that is equivalent to 4 spaces. | ||||||||||||
Type
cin >> |
Replace the scanf statement with the cin statement. | ||||||||||||
Click on Save | Now click on Save | ||||||||||||
Let us execute the program and see | |||||||||||||
On the terminal | Come back to the terminal | ||||||||||||
Type
g++ array.cpp -o arr Type ./arr |
To comple type,
g++ array.cpp -o arr To execute ./arr | ||||||||||||
Here the output is displayed as,
The sum is 6. | |||||||||||||
Summary | In this turoial we learnt,
To add elements in a 2D array. To print 2D array. To calculate the sum of 2D array. | ||||||||||||
Assignment: | Write a program that takes two 2D arrays as input.
Subtract them and find the result. | ||||||||||||
Slide 4
About the Spoken Tutorial Project
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* Watch the video available at the following link
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Slide 5
Spoken Tutorial Workshops The Spoken Tutorial Project Team
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The Spoken Tutorial Project Team * Conducts workshops using spoken tutorials
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Slide 6
Acknowledgement
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Spoken Tutorial Project is a part of the Talk to a Teacher project
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Remain on previous slide
No slide for this part |
This is Ritwik Joshi from IIT Bombay.
Thank you for joining. |