introduction to programming end show. resource team r.p ranjan-lecturer, spictec, galle. w.m.a.s....
TRANSCRIPT
Resource Team
R.P Ranjan-Lecturer, SPICTEC, Galle.
W.M.A.S . Wijesekara-Centre manager,CRC Hali-Ela
H.P.U.S Indra Kumara-Instructor,CRC Hanguranketha
R.M.P Bandara-Lecturer,CPICTEC Gurudeniya
K.M.P.U Wimalaweera-Instructor,CRC Polonnaruwa
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What is a computer program?
A computer program is a set of instructions or commands, which tell the computer what to do.
A computer language is a set of symbols and rules used in constructing programs.
Computer languages are used to develop application programs
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Cont….
The machine can understand only the machine language.
Assembly and other high level languages are not machine language.
To transform these languages into machine language, translators are needed.
Source Code Object CodeTranslator
Low Level Language
High Level Language
1st Generation
2nd Generation
3rd Generation
4th Generation
5th Generation
Computer Language
Classification of Programming Languages
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Generation of programming languages
1st Generation language ( 1GL )
2nd Generation languages( 2GL )
3rd Generation languages ( 3GL )
4th Generation languages ( 4GL )
5th Generation languages ( 5GL )
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1st Generation language ( 1GL )
Machine level programming language
Machine code is the binary digit language
It consists of 1s and 0s.
The machine can directly execute the machine code
Execution is speedy because no translators are used.
It is very difficult to write and modify programs.
It is machine dependant, because machine-language instructions vary according to computer architecture.
It is a low level language
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2nd Generation languages( 2GL )
Assembly language is used
Assembler is used to convert assembly language to machine language
Mnemonics and variables are used to write codes
It is a machine dependant language
Difficult to write and modify programs
It is a low level language
Execution is fast
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3rd Generation languages ( 3GL )
It is easy to understand, because it is similar to human languages
Translators are used to convert high level language to machine language
Compilers or interpreters are used as translators.
Some of the 3rd generation languages are unstructured languages such as Basic
It is easy write and modify programs
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3rd Generation languages ( 3GL )
many of the third generation languages are procedural languages because the program instructions comprise a list of steps or procedures
They are not machine dependent languages
One instruction in a third generation language can replace many assembly language instructions
programmer has to describe how it should be done.
Ex : Basic, Fortran, Cobol, Pascal
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4th Generation languages ( 4GL )
Introduced in the late 1980s
They are designed to reduce programming effort
It consumes less time to write a program
They are non procedural languages
Very easy to write and modify
One instruction in 4GL can replace a number of 3GL instructions
Programmer has to describe what is to be done.
4GL languages reduce software development cost.
They are described as application development without programmers
Ex : FOCUS, IDEAL, dbase III plus
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5th Generation languages ( 5GL )
Introduced in the early 1990s
User-friendly Graphical User Interfaces are facilitated.
Very easy to write and modify program
Execution speed is low
Event driven programs were introduced
Ex: Visual basic, Visual C++, Small Talk
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Low Level Languages
First and second generation languages are considered low level languages.
They are machine dependant languages
These languages are close to the hardware
The programmer should have hardware knowledge to write a program
Productivity is low
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High Level Languages
3GL,4GL and 5GL are considered high level languages
They are machine independent languages
It is easy to write and modify
The programmer does not need knowledge of hardware to write programs
Productivity is high
Consume less time to write programs
5GL allow user-friendly facilities
Translators need to be used to convert to machine language
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Translators
Translator is used to convert source code into object code. these are of three types
1. Assembler
2. Interpreter
3. Compiler
Source Code Object CodeTranslator
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Assembler
is a low-level language Translator.
is a software program that converts assembly language into machine language.
converts mnemonics into machine code
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Interpreter
is a translator that goes through the process of translation every time the program is run.
is found running some versions of BASIC, where it translates one line of the program at a time.