True, #undef can be used only on a macro that has been #define earlier

Example: #define PI 3.14

We can undefine PI macro by #undef PI

True, After preprocessing all the macro in the program are removed.

False, the preprocessor directive is not mandatory in any c program.

True, the header file contains classes, function prototypes, structure declaration, macros.

False, Always the macro is substituted by the given text/expression.

FALSE

Example: #define symbol replacement

When the preprocessor encounters #define directive, it replaces any occurrence of symbol in the rest of the code by replacement. This replacement can be an statement or expression or a block or simple text.

FALSE, The macro is case insensitive.

True, A macro may have arguments.

Example: #define CUBE(X)(X*X*X)

False, The scope of macros is globals and functions. Also the scope of macros is only from the point of definition to the end of the file.

True, We can prevent the same file from getting included again by using a preprocessor directive called #ifndef (short for "if not defined") to determine whether we've already defined a preprocessor symbol called XSTRING_H. If we have already defined this symbol, the compiler will ignore the rest of the file until it sees a #endif (which in this case is at the end of the file).

#ifndef XSTRING_H

#define XSTRING_H defines the same preprocessor symbol,

Finally, the last line of the file, #endif