How are Programs Understood by the Computer?

•Compiler: is a program whose task is to accept as input a source program written in a certain high-level language and to produce as output an object code or assembly code.

•Interpreter: is a program that ultimately performs the same function as a compiler, but in a different manner. It works by scanning through the source program instruction by instruction. As each instruction is encountered, the interpreter translates it into machine code and executes it directly.

•Assembler: is a program that automatically translates the source program written in assembly language and to produce as output an object code written in binary machine code.

•Linker: is a program that takes one or more objects generated by compilers and assembles them into a single executable program.

•Loader: (is a routine that) loads an object program into memory of the processor and prepares it for execution

Compiler

•A program whose task is to accept as input a source program written in a certain high-level language and to produce as output an object code which can be run on the computer.

Assembler

•A program that automatically translates the source program written in assembly language and to produce as output an object code written in binary machine code.

Interpreter

•A program that ultimately performs the same function as a compiler, but in a different manner. It works by scanning through the source program instruction by instruction. As each instruction is encountered, the interpreter translates it into m/c code and executes it directly.

Comparison between Compiler and Interpreter

Compiler:

-Converts the source code program into m/c code before program execution

-Can be removed from memory after compilation is finished

-Compilation is faster, translation occurs with program execution

-Compilation results in an object code on direct execution

-More complicated error checking

Interpreter:

-Converts each source program line into m/c code as it executes, line by line.

-Must be continuously resident in memory while the program is being executed

-Interpretation is slower. There is no concurrent translation and so consumes time

-No object code results for that can be executed later

 -Easier error checking

linker

Is a program that takes one or more objects generated by compilers and assembles them into a single executable program.

Figure of the linking process, where object files and static libraries are assembled into a new library or executable.