C-and-C++/C3/Working-With-2D-Arrays/English
Title of script: Working with 2D arrays
Author: Ashwini Patil
Keywords: : 2D arrays, Matrix addition, video tutorial()
|
| ||||||||||||
Slide 1 | Welcome to the spoken-tutorial on 2dimensional Arrays in C and C++. | ||||||||||||
Slide 2 | In this tutorial we will learn,
What is a 2Dimensional array. We will do this with the help of an example. | ||||||||||||
Slide 3 | To record this tutorial, I am using
Ubuntu Operating System version 11.10, 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.
Starting index of a matrix or array in C and C++ is always 0. Here we see a 2dimensional array in a row column matrix. Starting index is 0. | ||||||||||||
Slide 5 | Now let us see how to declare 2 dimensional array
The Syntax for this is: data-type arr_name[row] and [col]; eg.here we have declared a 2dimensional array num with 2rows and 3columns. int num[2][3]; | ||||||||||||
On the editor | Now let us see an example.
I have already typed the program. Let me open it. | ||||||||||||
Point to array.c | Note that our file name is 2d-array.c
In this program we will calculate the sum of the elements of the 2dimensional arrays. Let me explain the code now. | ||||||||||||
Highlight
#include <stdio.h> |
This is our header file. | ||||||||||||
Highlight
int main() |
This is our main function. | ||||||||||||
Highlight
int i,j;
|
Here, we have declared variable i and j. | ||||||||||||
Highlight
int num1[3][4],num2[3][4]; |
Then we have declared num1 with 3rows and 4columns
And num2 again with 3rows and 4columns | ||||||||||||
Highlight
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]); |
num1 and num2 are 2dimensional arrays.
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 and 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. | ||||||||||||
Highlight
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]); |
Similarly here we take elements of the matrix num2 as input from the user.
| ||||||||||||
Highlight
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
Here %3d is used to align the matrix on the terminal. | ||||||||||||
Highlight
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"); } |
Now here we display the matrix num2 | ||||||||||||
Highlight
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"); } |
Then we add the num1 matrix and the num2 matrix
And display the result | ||||||||||||
Highlight
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 your keyboard. | ||||||||||||
On the terminal
Type gcc array.c -o arr ./arr |
To compile type,
gcc space 2d-array.c space -o space arr and Press enter To execute type, ./arr Now Press enter | ||||||||||||
Enter values from 1 to 12
|
Here we see:
Enter the element of 3X4 array num1 I will enter the values now. Now we can see, Enter the elements of 3X4 array num2: I will enter the values. The output is displayed. | ||||||||||||
Highlight num1 matrix | Here we can see the num1 matrix. | ||||||||||||
Highlight num2 matrix | Here we can see the num2 matrix. | ||||||||||||
Highlight the sum. | And this is sum of num1 and num2 | ||||||||||||
Now we will see how to execute the same program in C++.
I have already made the program. I will oepn it and explain. | |||||||||||||
Point the cursor to the filename
2d-array.cpp |
- | Enter values from 1 to 12
|
Here we see:
Enter the element of 3X4 array num1 I will enter the values now. Now we can see, Enter the elements of 3X4 array num2: I will enter the values. The output is displayed. | ||||||||||
Highlight num1 matrix | Here we can see the num1 matrix. | ||||||||||||
Highlight num2 matrix | Here we can see the num2 matrix. | ||||||||||||
Highlight the sum. | And this is sum of num1 and num2 | ||||||||||||
Now we will see how to execute the same program in C++.
I have already made the program. I will oepn it and explain. | |||||||||||||
Highlight
include<iostream> |
This is our header file as “iostream”. | ||||||||||||
Highlight
using namespace std |
This is our “ using” statement. | ||||||||||||
Highlight
int main() |
This is our main function. | ||||||||||||
Highlight
cout and cin |
Here we have cout function as we use cout to print the ouput in C++
Then we have “cin function. We use cin to read a line in C++. | ||||||||||||
Highlight
/t |
Here we use /t it means horizontal tab that is equivalent to 4 spaces.
Rest of the code is similar to our C code. | ||||||||||||
Click on Save | Now click on save. | ||||||||||||
On the terminal | Let us execute come back to our terminal.
Let me clear the prompt. | ||||||||||||
Type
g++ array.cpp -o arr Type ./arr |
To comple type,
g++ space array.cpp space -o space arr1 Press Enter To execute type ./arr1 Press Enter | ||||||||||||
Enter values from 1 to 12
|
Here we see:
Enter the element of 3X4 array num1 I will enter the values. Now we see, Enter the elements of 3X4 array num2: I will give the values as The output is displayed. | ||||||||||||
Highlight
num1 matrix |
We can see the num1 matrix. | ||||||||||||
Highlight
num2 matrix |
The num2 matrix. | ||||||||||||
Highlight
The sum |
And this is sum of num1 and num2
This brings us to the end of this tutorial. Come back to our slides | ||||||||||||
Summary | Let us summarize:
In this turoial we learnt, To add elements in a 2D array. To print 2D array. And 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
|
* Watch the video available at the link shown below
| ||||||||||||
Slide 5
Spoken Tutorial Workshops The Spoken Tutorial Project Team
|
The Spoken Tutorial Project Team * Conducts workshops using spoken tutorials
| ||||||||||||
Slide 6
Acknowledgement
|
Spoken Tutorial Project is a part of the Talk to a Teacher project
| ||||||||||||
Remain on previous slide
No slide for this part |
This is Ritwik Joshi from IIT Bombay.
Thank you for joining. |