Q Is the C preprocessor part of the C compiler?
A No. The C preprocessor is not part of the C compiler. With its own line-oriented grammar and syntax, the C preprocessor runs before the compiler in order to handle named constants, macros, and inclusion of files.
Q How do you remove a macro name?
A By putting a macro name after the #undef directive, the macro name can be removed. According to the ANSI C standard, a macro name has to be removed before it can be redefined.
Q Why do you need the #endif directive?
A The #endif directive is used with an #if, #ifdef, or #ifndef directive because statements under the control of a conditional preprocessor directive are not enclosed in braces ({ and }). Therefore, #endif must be employed to mark the end of the block of statements.
Q Can the conditional expression following the #if directive be an arithmetic expression?
A Yes. The conditional expression evaluated by the #if directive can be an arithmetic expression. If the expression returns a nonzero value, the code between the #if directive and the next nearest directive are included for compilation. Otherwise, the code is skipped.
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