Here the topic discussed is pre processor directives. The C preprocessor is a macro processor that is used automatically by the C compiler to transform your program before actual compilation (Proprocessor direcives are executed before compilation.). ... Macro is defined by #define directive. Preprocessing directives are lines in your program that start with #. #define #preprocessordirectives #preprocessors #definepreprocessordirectives #cprogramming #cprogramforpreprocessordirectives #definecprogramfull #difinecprogramdemonstration #definepreprocesor