List the cousins (context) of compiler and explain the role of any one of them

List the cousins (context) of compiler and explain the role of any one of them.

• The cousins of compiler are :

1. Pre-processor
2. Assembler
3. Linker
4. Loader

1. Pre-processor : 

• Pre-processor produce input to compiler they may perform the following functions :

    a) Macro Processing : 

• A pre-processor may allow user to define macros that are shorthand for longer constructs.

    

    b) File Inclusion : 

• A preprocessor may include the header file into the program text.

    c) Rational Pre-processor : 

• Such a preprocessor provides the user with built in macro for construct like while statement or if statement.

    d) Language Extensions : 

• this processors attempt to add capabilities to the language by what amount to built-in macros.
• Ex: the language equal is a database query language embedded in C. 
• statement beginning with ## are taken by preprocessor to be database access statement unrelated to C and translated into procedure call on routines that perform the database access.

Fig.Context Of Compiler

2. Assembler :

• Assembler is a translator which takes the assembly program as an input and generates the machine code as a output. An assembly is a mnemonic version of machine code, in which names are used instead of binary codes for operations.

3. Linker :

• Linker allows us to make a single program from a several files of relocatable machine code. These file may have been the result of several different compilation, and one or more may be library files of routine provided by a system.

4. Loader :

• The process of loading consists of taking relocatable machine code, altering the relocatable address and placing the altered instructions and data in memory at the proper location.