basic programming

1. INTRODUCTION
TO BASIC
COMPUTER
PROGRAMMING
Prepared by:
Vic Allen Leonel De Castro
& Carlito Redoble

2. Program is a set of step-by-step instructions that tells or
directs the computer what to do. It sequences the tasks a
user wants to be done and produces the results or output
needed.
The set rules or instructions that tells the computer what
to perform is done through programming language.There
are various types of programming language you can choose
from.
A programmer is the person who designs a program. It
converts problem solutions into instructions for the
computer.The programmer designs the program, decides
which of the programs or set of instructions to use and tests
the program to see if it is working as designed.
Introduction to programming

3. Program life cycle
 The steps to follow in writing or creating
a program includes the following:
1. Identify the problem – this is the first
step. As it gives the desired output
requirements, you are to analyze the need to be able to come up
with a suitable programming solution.
1. Planning the solution
 Two ways (these two are used only to plan the solution):
 Draw flowchart – graphical representation of step-by-step
instruction to be done in a program.
 Write a pseudo code – list down the set of instructions to be used in
the program
3. Coding the program – code the program with the use of a chosen
programming language (in this presentation, we’ll use visual basic
as our programming language.

4. 3. Testing the program
 Desk checking – mentally
traces/checs the logic of the
program to make sure that it is error free.
 Translation – the programming language uses a
translator to ensure that the programmer does not
violate any language rules by the chosen programming
language.
 Debugging – detecting , locating and correcting bugs
(error or mistake)
5. Documentation – contains a brief narrative procces
undergone by the program, from the identification of the
problem, planning the solution through flowcharting and
psuedo code, coding of the program up to the testing
result.

5. Levels of programming
language
1. Machine Language or First Generation Programming
Language – lowest level of programming.
2. Assemble Language or Second Generation
Programming Language – considered as low level
language uses Mnemonic codes ( abbreviations that
easy to remember).
3. High Level Laguage orThird Generation Programming
Language(3GL) – language is written in English like
manner.
4. Very High Level Language or Fourth Generation
Language (4GL)
5. Natural Language – fifth generation languages
resemblance to English language.

6. Procedural and non-procedural
languages
PROCEDURAL LANGUAGE
 Programming language which are considered procedural
uses a series of instructions or statements which are
sequential from the beggining to the end.
Examples of procedural language are :
 BASIC ( Beginners’s All-Purpose Symbolic Instruction
Code)
 COBOL ( Common Business Oriented Language)
 PASCAL
 FORTRAN ( FormulaTranslator )
 C
 PL1 ( Programming Language 1 )

7. Non-Procedural Languages
 These programming languages ate considered as
object-oriented programming languages.They
are event-drivenwhich means that a
programmer selects an event that needs to occur
before the instruction or statement is exsicuted.
Examples of events are click, double click, drag
and drop , mouse over and other event .
Examples of non-procedural languages are :
VISUAL BASIC
C++
JAVA
DELPHI

8. Beginning Commands
There are also special functions called "commands" (also
called "instructions"). A "command" tells the QBasic
interpreter to do something. Ex: PRINT, CLS, and INPUT. I will
also introduce you to variables.
 PRINT
It simply PRINTs the words you specify to the screen.The syntax
for PRINT is PRINT “ ” or ?“ ” . Put what you want to show up on
the screen inside the quotes. Ex. PRINT "Hello World!“.Then the
screen will print Hello World!
 CLS
CLS stands for Clear Screen. It does what it stands for, it clears the
entire screen.The syntax for this is, of course, CLS.
QBasic Tutorial

9.  VARIABLES
Variables are used to store information in your computers memory.
Think of them as storage boxes in your computer.They are almost
ALWAYS used in a program.To declare a variable just do this: A(ex)
= 10. A is now storing the word "hello". So when you PRINT A then
10 will be printed in the screen as an output.You can use any
word,number, or letter as your variable.
 INPUT
INPUT is also used to restore value in a variable. Ex. INPUT x, a
question mark will be printed on the screen asking for a value.
INPUT is also used to ask a printed question, ex. INPUT “number”;x
The screen will show, number?__ ,asking value for the x.You can
also use comma instead of a semicolon.
Note: If you put a semicolon then a question mark appears after the
prompt string. If you put a comma, then no question mark appears.

10. Expressions
An expression is something the interpreter
calculates (or evaluates). Such as:
1 + 1 (addition)
100 - 47 (subtraction)
3 * 34 (multiplication)
80 / 4 (division)
Note:The computer will always follow the PMDAS
pattern in calculating/solving expressions.

11. IF, THEN, ELSE
IF ANDTHEN
 The IF andTHEN commands are used to
compare an expression and then perform
some task based on that expression
Example:
x = 5
IF x = 5 then PRINT “ x is equal to 5 ”
Since x is equal to 5, the program will print:
x is equal to 5

12. ELSE
 Using the ELSE command, you can have the
program perform a diffrent action if the
statement is false.
Example:
x = 3
IF x = 5THEN PRINT “Yes” ELSE PRINT “No”
Since x is not equal to 5, the output is:
No

13. END IF
END IF allows you to have multiple
commands after the if . . .THEN
statement, but they must start on the line
after the IF statement . IF should appear
right after the list commands.

14. Expression Signs
You can also enter the following statements, instead of
the equals signs:
X < 5 (x is less than 5)
X > 5(x is greater than 5)
Run the Following :
X = 16
IF (X>5)THEN PRINT “ x is greater than 5 ” ELSE PRINT
“x is lesser than 5”
Output :
X is greater than 5

15. You can also combines the signs like this:
X <= 5 (is less than or equal to 5)
X >= (x is greater than or equal to 5)
X <> 5 ( x does not equal 5)
YOU CAN COMBINE ALL
THIS KNOWLEDGE IN THIS
PRESENTATION USING
Qbasic.. 

16. Presented by:
Vic Allen
Leonel
De Castro
Carlito
Redoble