C Preprocessor — Part 1 MCQs with Explanations

Since the #define replaces the string int by the macro char . So, here i is a variable of type char and not int .

The macro call square(4) will be substituted by 4*4 so the expression becomes i = 64/4*4 . Since / and * has equal priority and associativity left to right, so the expression will be evaluated as (64/4)*4 i.e. 16*4 = 64.

The preprocessor directives can be redefined anywhere in the program. So the most recently assigned value will be taken.

Preprocessor executes as a seperate pass before the execution of the compiler. So textual replacement of clrscr() to 100 occurs.The input program to compiler looks like this : void main () { 100; printf ( " %d \n ", 100 ) ; } Note: 100; is an executable statement but with no action. So it doesn't give any problem.

The macro expands and evaluates to as: x+2*y-1 => x+(2*y)-1 => 10

main.c: In function ‘main’: main.c:5:12: error: lvalue required as increment operand i = max++;

## is token pasting operator which simply combines all the parameters of macro into one variable. So, in f(var, 12), var and 12 combines to form var12 and replaces the f(var, 12) and hence the output is 100.

L value is required for this expression (x++) which is illegal.

Preprocess code before compilation is the correct answer to “What is the purpose of the C preprocessor in C programming”. This question is standard in competitive examination syllabi for C Preprocessor.

#include is the correct answer to “Which directive is used to include the contents of another file in a C program using the C preprocessor”. This question is standard in competitive examination syllabi for C Preprocessor.

To define a macro is the correct answer to “What is the purpose of the #define directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

#if is the correct answer to “In C, which directive is used to conditionally include code based on preprocessor macros”. This question is standard in competitive examination syllabi for C Preprocessor.

The code block following it is included is the correct answer to “What is the result of the #ifdef DEBUG directive if the DEBUG macro is defined”. This question is standard in competitive examination syllabi for C Preprocessor.

#define is the correct answer to “Which directive in C preprocessing is used to define a macro with parameters”. This question is standard in competitive examination syllabi for C Preprocessor.

To undefine a macro is the correct answer to “In C preprocessing, what is the purpose of the #undef directive”. This question is standard in competitive examination syllabi for C Preprocessor.

Checks if a macro is not defined is the correct answer to “What does the #ifndef directive do in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Provides compiler-specific instructions is the correct answer to “In C, what does the #pragma directive do in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

To include a header file is the correct answer to “What is the purpose of the #include directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

To conditionally include code is the correct answer to “What is the purpose of the #if directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

#ifdef MACRO is the correct answer to “In C, how do you use the #ifdef directive to conditionally include code if a macro is defined”. This question is standard in competitive examination syllabi for C Preprocessor.

To include an error message in the code is the correct answer to “What is the purpose of the #error directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

The code block following it is excluded is the correct answer to “What is the result of the #ifndef DEBUG directive if the DEBUG macro is defined”. This question is standard in competitive examination syllabi for C Preprocessor.

#define is the correct answer to “Which directive in C preprocessing is used to concatenate two or more strings”. This question is standard in competitive examination syllabi for C Preprocessor.

Specifies the line number in the source file is the correct answer to “In C, what does the #line directive do in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Prevents recursive inclusion of header files is the correct answer to “What is the purpose of the #pragma once directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Provides an alternative condition is the correct answer to “In C preprocessing, what is the purpose of the #elif directive”. This question is standard in competitive examination syllabi for C Preprocessor.

Generates a compilation error with a specified error message is the correct answer to “What is the result of the #error directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Includes a message in the code is the correct answer to “What is the purpose of the #pragma message directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

#ifndef MACRO is the correct answer to “In C, how do you use the #ifndef directive to conditionally include code if a macro is not defined”. This question is standard in competitive examination syllabi for C Preprocessor.

Prevents multiple inclusion of header files is the correct answer to “What does the #pragma once directive do in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Checks if a macro is defined is the correct answer to “In C, what is the purpose of the #ifdef directive”. This question is standard in competitive examination syllabi for C Preprocessor.

Generates a warning message is the correct answer to “What is the purpose of the #pragma warning directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Provides an alternative condition is the correct answer to “In C preprocessing, what is the purpose of the #elifdef directive”. This question is standard in competitive examination syllabi for C Preprocessor.

Includes a message in the code is the correct answer to “What is the result of the #pragma message directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Undefines a macro is the correct answer to “What is the purpose of the #undef directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Checks if a macro is not defined is the correct answer to “In C preprocessing, what is the purpose of the #elifndef directive”. This question is standard in competitive examination syllabi for C Preprocessor.

Generates a warning message is the correct answer to “What is the result of the #pragma warning directive in C preprocessing”. This question is standard in competitive examination syllabi for C Preprocessor.

Specifies the line number and filename in the source file is the correct answer to “In C, what is the purpose of the #line directive”. This question is standard in competitive examination syllabi for C Preprocessor.

All of the above is the correct answer to “C preprocessor”. This question is standard in competitive examination syllabi for C Preprocessor.

has # as the first character is the correct answer to “A preprocessor command”. This question is standard in competitive examination syllabi for C Preprocessor.