Basic Introduction to Computer Programming.ppt

Computer Programming
 Computer programming is the process of
writing instructions that direct a computer to
carry out specific tasks
 A computer program is a set of step-by-
step instructions that tell a computer how to
solve a problem or carry out a task
 The instructions that make up a computer program
are often referred to as code
 A program is written in a computer programming
language

Programming Languages (-1-)
 A programming language is an artificial
language designed for creating instructions that a
computer can carry out
 In contrast, the languages we speak [e.g., English / Urdu] are
natural languages
 Programming languages differ from natural
languages in that
 natural languages are used for interaction between people
 programming languages allow humans to communicate
instructions to machines as well as machine-to-machine
interaction

Programming Languages (-2-)
 Programming languages can be divided into two major
categories
 Low-level languages
 Require the programmer to write instructions for the lowest level of
computer’s hardware
 Easy for computer to understand; Difficult for humans
 Examples: Machine Language, Assembly Language
 High-level languages
 Makes programming process easier by providing commands such
as PRINT or WRITE instead of unintelligible strings of 1s and 0s
 Examples: FORTRAN, C, C++, Java, Python …
 Languages can also be categorized by generations

LOW-LEVEL
LANGUAGES
Programming Language
Categorization
HARDWARE
MACHINE LANGUAGE
ASSEMBLY
LANGUAGE
HIGH-LEVEL
LANGUAGES
1st
Generation
Language [1GL]
2GL
3GL, 4GL

Machine Language /
Machine Code
 The first languages for programming computers – sometimes
referred to as first-generation languages
 A machine language consists of a set of commands,
represented as a series of 1s and 0s, corresponding to the
instruction set understood by a microprocessor
 A machine language is specific to a particular CPU or
microprocessor family
 High-level languages are (mostly) translated [compiled] to
machine language in order to be understood and executed by
the microprocessor

Example
Add the registers 1 and 2. Place the result in
register 6.
[ op | rs | rt | rd | shamt | funct ]
0 1 2 6 0 32
decimal 000000 00001 00010 00110 00000
100000 binary
Machine Language /
Machine Code

Assembly Language
 Allows programmers to use abbreviated
command words rather than 1s and 0s used in
machine languages
 A significant improvement over machine languages
 Mnemonics such as ADD, SUB, MUL, DIV, JMP etc are
more understandable than 0001, 0100 etc
 Also referred to as second-generation languages
 Assembly languages are also machine specific
 Each assembly language command corresponds on a
one-to-one basis to a machine language instruction

Assembly Language
Example 1
Add 10 to the variable MARKS
ADD MARKS, 10
Example 2
Transfer the value 10 to the AL register
MOV AL, 10

High-level languages
C/C++, JAVA, BASIC and etc.
 Similar to everyday English,
 Use mathematical notations
Example 1
Add 10 to the variable MARKS
MARKS = MARKS + 10;
Example 2
Assign the value 10 to the variable A, value 20 to variable B,
add them and store the results in variable C
A = 10; B = 20;
C = A + B;

Next
 Now we move on to: C How to Program

Basic Introduction to Computer Programming.ppt

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