Modular
Programming
Questions and Answers [25]
1.
Modular programming [SEE 2075 U]
[SLC 2066] [SEE 2065 S] [MM 2076] [PMT 2075K]
Modular
programming is a technique used to divide program into many small, manageable,
logical and functional modules or blocks.
2. Qbasic
is called Modular Programming [MFT 2075] [SQE 2074K]
QBasic is called modular programming because it
divides program into many small, manageable, logical and functional modules or
blocks.
3. Advantages
of modular programming [SEE 2073 U] [MFT 2075] [SQE 2074K]
i) Different programmers can
design different program modules independently, which is required in a large
and complex program.
ii) It is easy to design code and test the program modules independently.
iii) It is possible to use a single module in different places which reduces
program codes.
4.
Main module
The top
level controlling section or the entry point in modular programming is called
main module.
5.
Sub module
Module is a
block of statement that solves a particular problem. Sub module is a program
which is written under the main module. A program may have one or more sub
modules under main module.
6. Procedure
[SLC 2072]
[SLC 2071] [SLC 2064] [SLC 2067] [SLC 2068 S] [SQE 2075K] [PMT
2075K]
Procedure is a block of
statements that solves a particular program.
Procedure
is a section of code which performs one or more specific tasks and can be
accessed from remote location.
There are two types of procedure
– SUB Procedure and FUNCTION procedure
7.
SUB procedure [SLC 2064] [SLC
2065] [SLC 2069 S] [MM 2076]
A SUB
procedure is a small, logical and manageable functional part of program which
prefers specific task and does not return any value. SUB-procedure is called by
CALL statement. SUB-procedure’s name does not accept data type symbol because
it does not need to return a value.
8.
FUNCTION procedure [SLC 2064]
[SLC 2065] [SLC 2069 S] [MM 2076]
A FUNCTION procedure is a small, logical and manageable functional part of a
program which performs specific task and returns single value to the main
program or calling module. FUNCTION-procedure is called by statement and
expression method. FUNCTION-procedure’s name accepts data type symbols such as
$, %, !, #, &, etc. and it depends on the type of value to be returned.
E.g.: FUNCTION REV$ returns string.
9. String
function [SEE 2074 U]
String function is used with
string it returns string value.
10. Numeric
function [SEE 2074 U]
Numeric function is used with
number it returns numeric value.
11.
Library functions [SQE 2074K]
Library functions
are built-in or readymade functions provided by QBASIC. E.g. MID$( ), LEN( ),
SQR( ) etc.
12.
User defined function [SLC 2066
S] [SQE 2074K]
Function
which is defined by the user according to the need is called user defined
function.
13. Parameters
[SEE 2074]
Parameters are variables that
will receive data (arguments value) sent to the procedures (SUB program and
FUNCTION). Formal parameters are called parameter.
14.
Arguments
Arguments
are the values that are sent to the procedures (SUB program and FUNCTION).
Actual or real parameters are called arguments.
15.
CALL statement [SLC 2071] [PMT
2075K]
The function of CALL statement is to transfer the control to another procedure.
16.
DECLARE statement
The function
of DECLARE statement is to declare procedure such as FUNCTION or SUB in modular
programming.
17.
DIM SHARED statement
i) It makes
variable accessible to all modules.
ii) It appears in main module/ program.
18. SHARED
[SLC 2071]
It
is used in the sub program to share the values of certain variables between
main module and sub program
19. COMMON
SHARED [SEE 2074 U]
It is used in the main program to
share variable list between main module and all sub programs. This statement is
used to declared variable global.
20. Local
Variable [SEE 2075 S2]
Variables which are declared inside
the procedure are called local variables. Local variables are not visible to
other modules or functions. Its value is protected from outside interference
and has no effect on the variables outside the procedures. Local variable can
access only in its own module.
21. Global
Variable [SEE 2075 S2]
Variables which are declared
outside the procedure are called global variables. Global variables are visible to other modules
or functions. Its values can be accessed from any procedure or module. Global
variable can be access throughout the program
22. Passing
arguments by value
When arguments are passed by
value it makes a duplicate copy of arguments and their values (constants) are
used directly in parameter. It doesn’t make any effect on values of variable
which are passed to a procedure even they are changed in the procedure. To pass
the argument by value, variable is enclosed in parenthesis.
23. Passing
arguments by reference
When arguments are passed by
reference the address of the variables are passed to the procedure. The changes
made in the procedure’s variable will affect the variables used at calling
module. By default the value is passed by reference.
24. Qbasic
Operators [MFT 2075] [SQE 2074K]
Operators are special symbols
that are meant for specific tasks or operators.
i) Arithmetic operators
ii) Relational operators
iii) Logical Operators
iv) String operator
25. Static
variable
The variable which is declared by
using the “STATIC” keyword is called static variable.
Handling
of data file
Questions and Answers [25]
1.
Data file
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 - 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. It takes long time to access if the data file
contains a large volume of data. In sequential access data file we cannot change
the existing entry or insert a new entry.
b)
Random
access files
2.
Program File
The
file which contains a set of instructions that are needed for data processing
is called program file.
3.
Mode of data file [SLC 2069]
Mode of data file means opening a sequential file
for one of the three modes of operation like output mode, input mode and append
mode.
4.
Modes of operation for opening a sequential file
a)
Output Mode: It is used to create a
new data file and write data in it. If the file already exists its current contents
will be destroyed.
b)
Input Mode: It is used to retrieve
records or contents of existing data file.
c)
Append Mode: It is used to add more
records in existing file. If the specified file does not exist APPEND mode
creates it.
5.
File number
The
number assigned to a file in order to identify it during processing is called
file number.
Write down the functions of:
6. OPEN statement: It opens a sequential file for one
of the three possible operations (reading, writing, appending).
7. WRITE statement [SEE 2075] [MM 2076]: It sends one or more data items to the specified file. It inserts commas between the data items.
It encloses strings in double quotation marks.
8.
PRINT#:
It adds
spaces between data items while storing data. It does not enclose strings in
double quotation marks.
9. CLOSE statement [SEE 2074] [SEE 2073: It closes one or all open files.
10. INPUT# statement [SEE 2075 U] [SEE 2075 S 2]: It reads data from the sequential data file.
11. EOF( ) function [SEE 2075 S 2]: It is used to test the end of records with in a file.
12. LINE INPUT statement: It reads the entire line or maximum
255 characters form the keyboard or the sequential file.
13. INPUT$ function: It reads the specified number of
characters form the data file.
14. NAME statement [SEE 2073] [SLC 2071 S]: The NAME statement renames a file on a diskette. Only file
name changes, data and program line remains intact.
15. KILL statement [SEE 2074]: The KILL statement deletes the file or files from the
specified drive and directory.
16. MKDIR statement [SEE 2075 U]: It creates a subdirectory which is used to manage files.
17. CHDIR statement: It allows QBASIC to change from one
directory to another.
18. RMDIR statement [SLC 2065] [SLC 2068 S]: It is used to remove or delete only the subdirectories from
a disk. It can remove only empty subdirectories.
19. FILES statement: The FILES statement displays the
files of the current sub directory or specified sub directory.
20. SHELL: The SHELL statement
allows a program to run external programs or command line statements in
Windows, MAC OS and Linux.
21. INT
[MM 2076] [MFT
2075]: It rounds and returns the largest integer less than or equal
to a numeric expression.
22. PRINT
[PMT 2075K] : Display
result on screen.
23. MID$ ( ) [MFT
2075]: It is a string
function that returns the specified number of characters from the specified
location of string.
24. LEN ( ) [SQE
2074K]: Returns
the number of characters in a string or the number of bytes required to store a
variable.
25. SQR ( ) [SQE
2074K]: Returns the square root of a
numeric expression.
