Top 100+ C Interview Questions | 2020

Top 100+ C Interview Questions | 2020

Introduction of C programming language

We are preparing this C Interview Questions post to benefit all the Engineering students by improving their programming skills and helping them out to shape their career in programming.

The questions included in this post are designed with the help of industry experts to be logical and engrossing.

We advise students to regularly follow this post and practice the questions so as to get a proper understanding of the programming concepts.

The language’s core philosophy is summarized as:

1. Beautiful is better than ugly.

2. Explicit is better than implicit.

3. Simple is better than complex.

4. Complex is better than complicated.

5. Readability counts.

What is Programming:

1· A programming language is a type of written language that tells computers what to do in order to work.

2· Programming languages are used to make all the computer programs and computer software.

3· A programming language is like a set of instructions that the computer follows to do something.

What is C Programming?

1· It is a programming language developed at AT & T’s Bell Laboratory,USA in 1972 by Dennis Richie.

2· It is a mid-level and procedural programming language.

3. Procedural programming is referred when large programs are broken down into smaller modules, and each module uses structured code.

4. This technique minimizes error and misinterpretation

Why learn C Language?

1· Learning C would provide a grip over basic elements of a programming language and would make learning any other programming language easy. C is reliable, simple and easy to use.

2. Moreover, in an industry where newer languages, tools and technologies emerge and vanish day in and day out, a language that has survived for more than 3 decades has to be really good.

3· Though many C++ and Java based programming tools and frameworks have evolved over the years the importance of C is still unchallenged.

Knowingly or unknowingly while using these frameworks and tools one would be still required to use the core C language elements.

Applications of C

1· Major parts of popular operating systems like Windows, UNIX, Linux is still written in C. This is because even today when it comes to performance (speed of execution) nothing beats C.

Moreover, if one is to extend the operating system to work with new devices one needs to write device driver programs. These programs are exclusively written in C.

2· The essence of all 3D computer games is speed.

3· Needless to say, such games won’t become popular if they take a long time to load.

4· To match the expectations of the player the game has to react fast to the user inputs.

5· This is where C language scores over other languages. Many popular gaming frameworks have been built using C language.

6· At times one is required to very closely interact with the hardware devices.

7· Since C provides several language elements that make this interaction feasible without compromising the performance it is the preferred choice of the programmer.

8. C program is used in Embedded Systems applications.

C vs Other Languages

1· C is known as the mother language because most of the compilers and JVMs (Java Virtual Machines) are written in C language.

2· Most of the languages which are developed after C language has borrowed heavily from it like C++, Python, Rust, JavaScript, etc. It introduces new core concepts like arrays, functions, file handling which are used in these languages.

3· Also, the performance of C is better than its succeeding higher programming languages

Mind Stimulating Programming Questions

1. Any programming language can be mastered only by getting a grip over the basics and fundamentals of it.

2. This section contains questions which test the foundations and fundamental concepts of C programming language.

3. Henceforth helping one to gain expertise of the language.

4. The questions in this section are often not straight forward but can be easily solved by applying logic and reasoning.

5. These questions have been made by referring several standard textbooks, websites, blogs.

6. Therefore ensuring you a quality practice time.

S.NO Questions – Part 1
1. What is the use of C programming language?
2. What are pointers in C?
3. What is null pointer in C?
4. Is the following C code valid?

#include <stdio.h>

int main()


char @name[2];

scanf(“%s”, @name);

printf(“%d”, @name);

return 0;


5. What will be the output of the following C code?

Input: I

#include <stdio.h>

int main()


char input_char;

char local_char;

scanf(“%c”, &input_char);

local_char = input_char;

printf(“%c”, local_char);

return 0;


6. Is the following C code valid?

Input: 3

#include <stdio.h>

int main()


int int;

scanf(“%d”, &int);

printf(“%d”, int);

return 0;


7. What are Arrays in C?
8. What will be the output of the following C code?

Input: 45 54

#include <stdio.h>

int main()


int a,b;

scanf(“%d %d”,&a,&b);

int c = a;


printf(“%d”, c);

return 0;

9. What will be the output of the following C code?

Input: 1.2145

# include <stdio.h>


int main(){

float num;

scanf(“%f”, &num);

printf(“%.2f”, num);

return 0;


Options: a. 1.21    b. 1.2145   c. 1.214500   d. 1.20

10. What will be the output of the following C code?

Input: S

# include <stdio.h>

int main(){

char c1;

scanf(“%c”, &c1);

printf(“%c”, c1);

return 0;


* Need Answers:  please contact us at email. (
S.NO Questions – Part 2
1. Is the following code valid?


int main()


char c = “S”;

printf(“%c”, c);

return 0;


2. What will be the output of the following C code?

Input 1 9

#include <stdio.h>

int main()


int a,b,c;

scanf(“%d %d”,&a,&b);




printf(“%d, %d”, a,b);

return 0;


3. Write a C Program to take input of two decimal numbers and print the result rounded to 4 decimals. Try implementing the program without declaring an additional variable to store the sum.

Test Cases:

1) Inputs: 1.2345   3.451223

2) Inputs: 1  3

4. Write a C Program to take the bio-data input – Full Name and Age of a user and print the details as shown in the test case. Try implementing using only one printf statement.

Test Case:


Ravi Varma


5. Write a program to take three integers as input, and print the product of the three integers. Note that you can declare and use maximum two variables.

Test Case:

Input: 4 5 10

Frequently Asked Questions in Companies

1. The questions in this section are prepared by discussing with real time developers in the software industry.

2. This section contains the most often asked C Programming interview questions.

3. Hence regularly practicing will be highly beneficial in clearing the technical interview round during placements.

4. We advise the students preparing for C Programming Interview to regularly follow our post and solve Frequently Asked Interview Questions

S.NO Questions – Part 1
1. In order to terminate the execution of a loop, we can use the ____ statement.

A) stop

B) pool

C) end

D) break

2. We can use “hello “+”world” to concatenate 2 strings in C.

A) True

B) False

3. In order to use string functions we must #include——

A) “cstring.h”

B) <ctype.h>

C) <string.h>

D) <cstring.h>

4. The function we can use to copy string to another string—?

A) strlen

B) strcpy

C) strcat

D) copy_string

5. C Style strings are terminated with an______

A) newline character

B) null character

C) nullptr

D) a blank space

6. A do-while loop is guaranteed to execute_____

A) indefinitely

B) until the programmer breaks out of it

C) at least zero times

D) at least one time

7. If you know a head of time how many times you need to loop, which loop would you use?

A) for loop

B) while loop

C) do-while loop

D) if else

8. A loop that is located inside another loop is called_

A) double loop

B) nested loop

C) inside-out loop

D) outside-in loop

People Asked Questions

1) This section comprises of questions asked by students/developers across various platforms like Quora, Youth4Work,etc.

2) PROCORP, has been answering many such questions in the respective platforms.

3) Hence solving/viewing such questions would clarify your doubts and get your concepts clear.

S.NO Questions – Part 1
1. How do I find prime number in a specific interval in C language?
2. What is %p in the printf function in C programming language?
3. How do I write code for two numbers passed as input N and X? The program must print the multiples of N (starting from 1) and must stop when the multiple is also divisible by X (using C language)
4. How can I print the following pattern using C++ programming language? I want loop structure involved in the code.


3 2

6 5 4

9 8 7 6

12 11 10 9 8

15 14 13 12 11 10




5. What will be the code to check whether a string contains only integer inputs or not in C language (inputs are taken by user at run time)?

1)If you are stuck at any question or need the answer to any question, just post the question number in the comment box and we will send you the answer instantly.
2)We advise the students preparing for C Programming Interview to regularly follow our post and solve C Interview Questions.

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