Programming language processors

Language Processors / Translator

Computer directly understands only machine language. Machine language is the native language of computer. Machine language is in binary form that is its instructions consists of strings of zeros and ones. A program written in high-level or assembly language cannot be run on a computer directly. Firstly, it is converted into machine language. So there is a need to translate the source program into object code for a computer to execute it. Language processor or translator may be defined as a software that converts source programs into object program. Therefore, a language translator software will take a source program(that cannot be understood by computer) as input and then will convert it into object code(that can be understood by computer).
Different types of language processors are:

1. •     Compilers
2. •     Interpreters
3. •     Assemblers

 

Compiler

A compiler is a program that converts the source program into object program(machine code) as a whole.
 A program written in high-level language is called source program. A program in machine language is called Object program. The compiler converts source program in machine code called object program. Compiler also checks and reports syntax errors in the program. A source program containing an error cannot be compiled.
For example, C language and COBOL uses compiler. The function of a compiler is shown in the figure above. 

Interpreter

 An interpreter is a program that converts one statement of a program into machine code at one time. Then translated instruction is executed. If there is an error in the statements, the interpreter displays an errors message. In other words we can say that interpreter is a software that translates an instruction into a machine language and gets executed it before proceeding to the next instruction.
The advantage of interpreters over compilers is that an error is found immediately. The disadvantage of interpreter is that it is not very efficient. It does not create object file. So every time we execute the source program, it is translated again one instruction at a time. Whereas compiler creates an object code file. So next time when the program is executed, this object program is run( and no translation or compilation is needed unless we change the source code). Visual Basic uses interpreter.

Assembler

An assembler is a translating program that translates the instructions of a program written in assembly language into machine language.

Q11. Differentiate between: Compiler & Interpreter, Software & Hardware, Source & Object Program, Low-level & High-level Language, DOS and Windows, 

Difference between Compiler & Interpreter

Difference between Compiler & Interpreter

Compiler	Interpreter
1.    Compiler   converts   a   program  into machine code as a whole.	1. Interpreter    converts    a    program   into machine code one statement at one time.
2.    Compiler creates object code file.	2. Interpreter does not create object code file.
3.    Program execution is fast. Since once program is compiled successfully, an object code file is produced. Now this object code file is executed. No need of re-compilation unless we change the source code.	3. Program execution is slow. Because every time we want to run a program it is interpreted again.
4.    Error detection and removal is comparatively difficult. Because, compiler will show a list of many errors in the whole program.	4. Error detection is instant and correction is relatively simple and easy, since only one line is translated at a time and if any error, then error message is displayed. We can correct one error at a time easily.