Compilation vs Interpretation in Programming

Compilation and Interpretation of Programs

• A compiler translates a high-level language program into an intermediate form called object code, which can be directly executed by the machine.
• An interpreter does not produce object code, but translates the source program line by line into machine language.

Examples of Compiled and Interpreted Languages

• Examples of compiled languages include: C, C++, C#, Ada, ALGOL, Java, COBOL, Visual Basic, Lisp, FORTRAN, Pascal
• Examples of interpreted languages include: QBASIC, JavaScript, PHP, ASP, APL

How a Compiler Works

• The parser is the brain of the compiler, knowing the syntax and grammatical rules of the source language.
• The parser uses a scanner to read in source program statements and break them into a sequence of tokens (words, numbers, identifiers, operators, etc.).
• The parser calls the code generator to produce object code, which performs the operation specified by the instruction.
• The process continues until the entire program has been read in and translated.

How an Interpreter Works

• An interpreter also has a parser that controls it, with a scanner that does the same job as the compiler's scanner.
• Instead of a code generator, an interpreter has an executor that directly executes the translated code.
• The interpreter translates the source program line by line into machine language, without producing object code.