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- Steve Jobs

C Preprocessor and Macros Interview Questions

In most of the MNC interview questions such as in ZOHO interview question, IVTL Infoview interview questions, Amazon interview questions, GOOGLE interview questions, Infosys interview questions and even in Voonik interview questions, We come across several Tricky C Questions about which 2:5 of the questions are from Preprocessor and Macros in c. Solving that kind of tricky C questions is not an easy task for all C programmers. We need more practices to solve it with ease. So we provide 25+ interesting C questions in Preprocessor and Macros to make your MNC interview very easy.

C Preprocessor and Macros Questions

21. What will be the output of the C program?

#include<stdio.h>
int main()
{	
	printf("Line :%d\n", __LINE__ );
	return 0;
}

A. 3 ✘

B. 6✘

C. Compilation error✘

D. 4✔

x

Option: D

Explanation

__LINE__ macro will print the number of lines from start to the statement containing __LINE__ thus outputted 4.

✉ Answer

22. What will be the output of the C program?

#include<stdio.h>
#define  preprocessor_works(x, y)  \
	printf(#x " and " #y " are great!\n")
int main(void) {
	preprocessor_works(you, me);
	return 0;
}

A. you and me are great!✔

B. #you and #me are great!✘

C. No output✘

D. Compilation error✘

x

Option: A

Explanation

# is know as Stringize or number-sign.

When # is used within a macro definition, # macro converts a macro parameter into a string constant.

When we are passing any special arguments or string as a parameter value, then # macrons are get used.

✉ Answer

23. What will be the output of the C program?

#include<stdio.h>
# define puts  "%s C preprocessor"
int main()
{
	printf(puts, puts);
	return 0;
}

A. Runtime error✘

B. Compilation error✘

C. %s C preprocessor %s C preprocessor✘

D. %s C preprocessor C preprocessor✔

x

Option: D

Explanation

printf(puts,puts); will call the preprocessor macro # define puts.

printf("%s C preprocessor","%s C preprocessor");

printf(%s C preprocessor C preprocessor);

✉ Answer

24. What will be the output of the C program?

#include<stdio.h>
#define preprocessor(n) printf ("macro" #n " = %d", macro##n)
int main(void) {
	int macro25 = 47;
	preprocessor(25);
	return 0;
}

A. Compilation error✘

B. macro25 = 47✔

C. macro47 = 25✘

D. Runtime error✘

x

Option: B

Explanation

## is nothing more than concatenation operator.

✉ Answer

25. What will be the output of the C program ?

#include<stdio.h>
#include<string.h>
#define MACRO(num) ++num 
int main()
{
	char *ptr = "preprocessor";
	int num =strlen(ptr);
	printf("%s  ", MACRO(ptr));
	printf("%d", MACRO(num));
	return 0;
}