programming languages compiler

7/28/2019 Programming Languages Compiler

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Overview of Programming Languages


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COMPUTER LANGUAGE A language is a system of communication.

A computer language is a means of communication usedto communicate between the people and the computer.

Computer programmer uses the computer language to

tell the computer what to do.


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BROAD CATEGORIES OF COMPUTER LANGUAGES

There are three categories of programming languages:

Machine language: language of 0 and 1 Assembly language: language of mnemonics High-Level language: language of English wordsand mathematical symbols.

Machine languages and assembly languages are alsocalled low-level languages


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P ROGRAMMING LANGUAGES Machine Language

Natural language of a particular computer.

Consists of strings of numbers(1s, 0s)

Instruct computer to perform elementaryoperations one at a time.

Machine dependant.


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Machine Language

Advantages : Fast and efficientMachine orientedNo translation required

Disadvantages :

Not portable Not programmer friendly


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PROGRAMMING LANGUAGES

Assembly Language

Assembly language programs use mnemonics torepresent machine instructions.

Translators programs called Assemblers to convertassembly language programs to machine language.

E.g. add overtime to base pay and store result in gross pay

LOAD BASEPAY

ADD OVERPAY

STORE GROSSPAY


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MACHINE LANGUAGE AND ASSEMBLY LANGUAGE

Compare the following codes :

Assembly code:MOV AX , var1

ADD AX , var2MOV var1 , AX

Machine Code:

1010 0001 0000 0000 0000 00000000 0011 0000 0110 0000 0000 0000 00101010 0011 0000 0000 0000 0000

Which one is easy to understand/remember?


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PROGRAMMING LANGUAGES

High-level languages

To speed up programming even further.Single statements for accomplishingsubstantial tasks.Translator programs called Compilers toconvert high-level programs into machine

language.E.g. add overtime to base pay and store resultin gross pay

grossPay = basePay + overtimePay


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HIGH -LEVEL LANGUAGES

Advantages : Portable or machine independentProgrammer-friendly

Disadvantages :

Not as efficient as low-level languages

Need to be translated

Examples : C, C++, Java, FORTRAN, Visual

Basic


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COMPILER

A compiler is a computer program thattransforms human readable source code of another computer program into the machine

readable code that a CPU can execute.

The act of transforming source code intomachine code is called "compilation".

Compiler converts all the files of a given projectat once.


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INTERPRETER

This is a software tool which interprets the user written code line by line, unlike compiler, which

processes everything at once.

In this case a single line is executed at a time. Itis time consuming and not used in real-timeapplications.


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LINKER

Linker uses the object files created by thecompiler and then uses the predefined libraryobjects to create an executable.

This executable is the one which is seen by thecommon user .


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ASSEMBLER

While compiler processes high level languages,assembler has the capability of processing onlythe low level assembly language.

This assembly language is extremely core(microprocessor/platform) specific.


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COMPILATION /L INKING A C program consists of source code in one or more filesEach source file is run through the preprocessor and compiler ,resulting in a file containing object codeObject files are tied together by the linker to form a single

executable program

Preprocessor/Compiler

Executable codea.out

Source codefile1.c

Object codefile1.o

Source codefile2.c Preprocessor/Compiler Object codefile2.o

Linker Libraries


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HOW TO COMPILE To compile and link a C program that is contained entirely in onesource file:cc program.c

The executable program is called a.out by default.If you dont like this name, choose another using the o option:

cc program.c o newname

To compile and link several C source files:cc main.c extra.c more.c

This will produce object (.o) files, that you can use in a later

compilation:cc main.o extra.o more.cHere, only more.c will be compiled the main.o and extra.o files willbe used for linking.

To produce object files, without linking, use -c:cc c main.c extra.c more.c

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