Scilab/C4/File-handling/English

Title of script: File Handling in Scilab

Author: Anuradha Amrutkar

Keywords: File Handling, writefile, read file, open file, close file

Visual Cue	Narration
Slide	Welcome to this spoken tutorial on File Handling using Scilab.
Slide	In this tutorial, we will learn File Handling with the following functions; Write Function Read Function mopen mclose
Slide	System Requirements For Demonstration i am using Ubuntu Linux12.04 operating system with Scilab version 5.3.3 installed
Slide	Pre-requisites: You should have Basic knowledge of Scilab. If not, for relevant spoken tutorials please visit spoken hyphen tutorial dot org
Slide	Now we will see some functions in scilab which are useful for File Handling. File Handling involves- writing to a file using write function, reading from a file using read function, opening an existing file using mopen function and closing an already opened file using mclose function.
	Let us start with writing data to a file. For this purpose the write() command is used.
Scilab Console --> random_matrix = rand(20,1) random_matrix = 0.2113249 0.7560439 0.0002211 0.3303271 0.6653811 0.6283918 0.8497452 0.6857310 0.8782165 0.0683740 0.5608486 0.6623569 0.7263507 0.1985144 0.5442573 0.2320748 0.2312237 0.2164633 0.8833888 0.6525135	Switch to the scilab console window. To begin with let us create a matrix of random numbers. Type; -->random underscore matrix is equal to rand in to bracket 20 comma 1 close the bracket semicolon and press enter
Scilab Console --> pwd	Now check the present working directory. Type -->pwd ans = /home/fossee In my case the present working directory is slash home slash fossee Make sure that you are in a directory where you have read & write permission , before you execute these commands.
--> write('random-numbers.txt', random_matrix)	Now we will write the content of variable random underscore matrix into a text file using the write command. Type;--> write into bracket into quotes random dash numbers dot txt close the quotes comma random underscore matrix close the bracket and press enter
	Let us see whether this file has been created. I will minimize the scilab console window. And open the file which will be created and saved in the fossee directory of my computer.
	You can see the data from variable random underscore matrix is written in a text file random dash numbers dot txt
Scilab Console -->new_vector = read('random-numbers.txt', 20, 1) new_vector = 0.2113249 0.7560439 0.0002211 0.3303271 0.6653811 0.6283918 0.8497452 0.6857310 0.8782165 0.0683740 0.5608486 0.6623569 0.7263507 0.1985144 0.5442573 0.2320748 0.2312237 0.2164633 0.8833888 0.6525135	I will close this file. Coming back to the scilab console. Now we will see how to read the data from a file. For this we will use the command read as follows, Typenew underscore vector is equal to read into bracket in to quote random dash numbers Dot txt close the quotes comma 20 comma 1 close the bracket and press enter. The read command reads all the data from the file mentioned in the argument, In this case random dash numbers dot txt, And stores in the variable new underscore vector Press Enter to continue the display
Narration: -->new_vector = read('random-numbers.txt', 19, 1)	If we modify the above command as new underscore vector is equal to read into bracket into quote random dash numbers Dot txt comma 19 comma 1 The read command reads only 19 data values from the file mentioned in this argument. In this case random dash numbers dot txt And stores in the variable new underscore vector. Issue this command on the scilab console and verify the output.
Slide	Now let us see about themopen function: fd = mopen(file-name, mode) mopen command is used to open an existing file in a way compatible to C fopen procedure. mode is a character string that controls whether the file is opened for r = Opens the file for reading. rb = Opens a binary file for reading. rt = Opens a text file for reading. w = Creates a new file for writing, or opens and truncates a file to zero length. wb = Creates a new binary file for writing, or opens and truncates a file to zero length. wt = Creates a text binary file for writing, or opens and truncates a file to zero length. a or ab = Appends (opens a file for writing at the end of the file, or creates a file for writing). r+ or r+b = Opens a file for update (reading and writing)
Scilab Console -->fd_r = mopen('random-numbers.txt','rt') fd_r = 1.	For eg fd underscore r is equal to mopen('random-numbers,'rt') the above command opens the 'random-numbers' as a text and read-only mode.
Slide	mclose(fd): mclose command closes the opened file by using mopen. mclose(fd) where fd is the file descriptor of the opened file If fd is omitted mclose closes the last opened file.
Summary	That's all we have in this tutorial. You have learnt - File Handling with the following functions: Write Function Read Function mopen mclose
Slide	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
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
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
	This is Anuradha Amrutkar from IIT Bombay Thank You for joining

Contributors and Content Editors

Lavitha Pereira, Sneha