Handling of Data File

1)     What is data file? What are the different types of data file?

Ans: The file which contains data given by the user to the program and information provided by the user to the computer is called data file.

The different types of data file are:

a.      Sequential Access files

b.     Random access files

2)     What is a file? Name the two types of data file in data processing.

Ans: A bunch of bytes stored on some storage device like magnetic tape, magnetic disk and optical disk is called file.

The two different types of file in data processing are:

a.      Program file

b.     Data file

3)     What do you mean by program file and data file?

Ans) The file which contains a set of instructions that are needed for data processing is called program file.

The file which contains only data that are required during data processing is called data file.

4)     What is sequential access data file?

Ans) A data file that stores a sequential data file containing name, address of some people in the same order or in sequential order is called sequential access data file.

5)     What are the disadvantages of sequential access data file?

Ans) The disadvantages of sequential access data file are:

a)     It takes long time to access if the data file contains a large volume of data.

b)     In sequential access data file we cannot change the existing entry or insert a new entry.

6)     Mention the difference between program files and data files.

Ans:

Program files	Data files
A program file has set of instructions needed for data processing.	A data file has collection of related data stored in a secondary storage.

7)     What are the difference between PRINT# and WRITE# statements?

Ans:

PRINT#	WRITE#
It adds spaces between data items while storing data.	It inserts commas between the data items.
It does not enclose strings in double quotation marks.	It encloses strings in double quotation marks.

8)     What is a file number?

Ans: The number assigned to a file in order to identify it during processing is called file number.

9)     List the modes of operations for opening a sequential file.
Ans: The modes of operation for opening a sequential file are:
i) Output Mode: It is used to create a new data file and write data in it.
ii) Input Mode: It is used to retrieve records or contents of existing data file.
iii) Append Mode: It is used to add more records in existing file.

10) Differentiate between output mode and append mode.
Ans:

OUTPUT mode	APPEND mode
i)  It creates a new file and prepares to write data to the file.	i) It opens an existing file and prepares to add data to the file.
ii) If the file already exists its current contents will be destroyed.	ii) If the specified file does not exist APPEND mode creates it.

11) Write down the functions of:
a) OPEN statement:
It opens a sequential file for one of the three possible operations (reading, writing, appending).
b) WRITE statement:
It sends one or more data items to the specified file.
c) CLOSE statement:
It closes one or all open files.
d) INPUT# statement:
It reads data from the sequential data file.
e) EOF() function:
It detects the end of the file marker reading the data from an open sequential file.
f) LINE INPUT statement:
It reads the entire line or maximum 255 characters form the keyboard or the sequential file.
g) INPUT$ function:
It reads the specified number of characters form the data file.
h) NAME statement:
The NAME statement renames a file on a diskette. Only file name changes, data and program line remains intact.
i) KILL statement:
The KILL statement deletes the file or files from the specified drive and directory.
j) MKDIR statement:
It creates a subdirectory which is used to manage files.
k) CHDIR statement:
It allows QBASIC to change from one directory to another.
l) RMDIR statement:
It is used to remove or delete only the subdirectories from a disk. It can remove only empty subdirectories.
m) FILES statement:

The FILES statement displays the files of the current sub directory or specified sub directory.