C-and-C++/C4/File-Handling-In-C/English

Title of script: Files in C & C++

Author: Ashwini Patil

Keywords: File handling, fopen, fclose

Visual Cue	Narration
Slide 1	Welcome to the spoken-tutorial on files in C.
Slide 2	In this tutorial we will learn how, To open a file. To read data from a file. To write data into a file. Few examples.
Slide 3	To record this tutorial, I am using, Ubuntu Operating System version 11.10, gcc Compiler version 4.6.1 on Ubuntu.
Slide 4	Let us start with the introduction to the files. File is a collection of data. It can be a database, a program, a letter or anything. We can create a file and access it using C. Now let us see an example on file hadling in C.
Point cursor to the filename file.c	I have a written program. Let's take a look. Note that our filename is file.c In this program we will create a file and write data into it.
Highlight #include <stdio.h>	Let me explain the code now This is our header file.
Highlight int main()	This is our main function.
Highlight FILE *fp;	To define a file variable we use the type FILE. The FILE variable is defined under the header stdio.h *fp is a pointer to the FILE variable. It will store all the information about the file. Like its name, status and current information. Let us go back to our slides.
Slide 5 fp = fopen(“filename”, “mode”);	Now we will see the syntax to oepn a file. Here, the fopen function opens a stream. Then it links the file with the stream. The filename is the name of the file that we want to open or create. We can give the path along with the filename. We can also give the extension. Here we can give the mode of the file.
Slide 6	Here, mode defines the following: w - creates file for read and write. r - opens file for reading. a – writing at the end of file.
Highlight fp = fopen(“Sample.txt”, “w”);	Now come back to our program. Here, we create a Sample.txt file in write mode. We can see that the path is given. Our file will be created on the desktop.
Highlight fprintf(fp,"This is just an example\n");	Then we will write the statements into the file. Welcome to the spoken-tutorial and This is an test example fprintf writes output to the given output stream.
Highlight fclose(fp);	fclose closes the file associated with the stream.
Highlught return 0;	This is our return statement.
Click on Save	Now Click on Save.
Type Ctrl, Alt and T keys	Now let us execute the program Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on you keyboard
Type gcc file.c -o file Type ./file	Let us compile type gcc file.c -o file to execute type Press Enter ./file
	We see the file is executed. Now we will check it out.
Click on home folder sign	Let us open the home folder. Click on the home folder option. Now click on the Desktop option.
Search for Sample.txt file	Here is our sample.txt file. This shows that our file is successfully created.
Double click on Sample.txt file	Now let us open. Double click on the file. We can see the messages here. Welcome to the Spoken Tutorial. This is an test example. This is how we create a file and write data into it.
To read data from file	Now we will see how to read data from a file.
	I have already made the program. I will open it. In this program we will read data from our sample.txt file and print the data on the console. Let me explain the code now.
Highlight #include <stdio.h>	This is our header file.
Highlight int main()	This is our main function.
Highlight FILE *fp	Here, a file variable and a pointer to the file variable is defined.
Highlight char c;	Then we have declared a character variable c.
Highlight fp = fopen("Sample.txt","r");	Here, we open the file Sample.txt in read mode. The output is stored in fp.
Highlight if (fp == NULL) printf("File doesn't exist\n");	Then we check the condition. If fp is equals to NULL. If the condition is true. Then we print the message: File doesn't exists.
Highlight else { while (c != EOF)	Else it will check for another condition. While c is not equal to EOF. Here, EOF is the end of file. It denotes the end of input. It is a condition where no more data can be read from a data source.
Highlight c = getc(fp);	If the condition is true. Then, It will display the characters from Sample.txt file on the console. Here, getc returns a character from a specified file or stream. Now it will return a character from Sample.txt file.
Highlight putchar(c);	putchar is used to display a character on the console. Then it will store the characters in variable c.
Highlight fclose(fp);	Here we close the file.
Highlight return 0;	And this is our return statement.
Click on Save	Now click on Save.
	Let us execute the program.
On the terminal	Come back to the terminal.
Type gcc readfile.c -o read Type ./read	To compile type gcc readfile.c -o read Now press enter To execute type ./read
Highlight Output	The output is displayed as: Welcome to the Spoken-Tutorial. This is an test example.
	This brings us to the end of this tutorial.
	Come back to our slides.
Slide 7	Let us summarize. In this tutorial we learned, File handling. To write data into a file. eg. fp = fopen(“Sample.txt”, “w”); To read data from a file. eg. fp = fopen(“Sample.txt”, “r”);
Slide 8 Assignment	As an assignment, Write a program to create a file TEST. Write your name and address in the file TEST. Then display it on the console using C program.
Slide 9 http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial About the Spoken Tutorial Project	Watch the video available at the link shown below It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Slide 10 Spoken Tutorial Workshops	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org
Slide 11 Acknowledgement	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro
	Ashwini Patil from IIT Bombay Thank You for joining

Contributors and Content Editors

Ashwini, Nancyvarkey, PoojaMoolya