What is macro pre-processor? Explain steps of macro preprocessor design

A macro preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is a preprocessed source code, which is then passed to the next program. The most common use of a preprocessor is as a part of the compilation process, in which the preprocessor manipulates and modifies the source code before the actual compilation.

The steps of macro preprocessor design are as follows:

1. Lexical Analysis: This is the first phase of preprocessing. In this phase, the preprocessor takes the source code as input and divides it into meaningful chunks, known as lexemes.

2. Macro Expansion: In this phase, the preprocessor replaces all the macro names in the source code with their respective definitions. Macros are a piece of code in a program which is given some name. Whenever this name is encountered by the compiler the compiler replaces the name with the actual piece of code.

3. File Inclusion: This is the phase where the preprocessor includes the contents of the header files into the source code program. The header files contain the definitions of functions and variables, which are used in the program.

4. Conditional Compilation: The preprocessor checks for any conditional directives in the source code. These directives allow the inclusion or exclusion of part of the source code based on certain conditions.

5. Line Control: In this phase, the preprocessor takes care of the lines of the source code. It may add or remove lines, or even change the line numbers.

6. Output: After all the above steps, the preprocessor produces a modified source code as output. This output is then passed to the compiler for the actual compilation.

These steps are followed in a sequence to design a macro preprocessor. The main aim of a macro preprocessor is to simplify the development and improve the readability and maintainability of the source code.