C Programming Practice Test: C Preprocessor — Flashcards

Quiz questions on pragma, stringizers, conditional preprocessor directives and token concatenation.

The C preprocessor is a macro processor that automatically transforms a program before compilation. It allows you to define macros, which are brief abbreviations for longer constructs. The preprocessor provides inclusion of header files, macro expansions, conditional compilation, and line control. It also makes three transformations on all input: Replaces C comments with single spaces, Deletes Backslash-Newline sequences, and Replaces predefined macro names with their expansions. 

The preprocessor is the first step in compiling a C program. It responds to directives in the code, which give it instructions on how to edit the source code. Pre-processing directives are lines in the program that start with the hash symbol #. 

Here are some preprocessor directives:
#if: Evaluates the expression or condition
#else: Evaluates the expression or condition if the condition of #if is false
#error: Indicates an error
#pragma: Provides additional information to the compiler 

You can define a macro in C using the #define preprocessor directive. For example, #define PI 3.1415.