Top 30 C Programming Interview Questions with Answers

Looking to brush up on your C programming theory before your next interview? Here in this blog post, we listed a comprehensive collection of C programming questions with answers to help you prepare for your next interview.

From basic concepts to advanced topics, our questions will test your understanding of the C programming language.

Gain a deeper knowledge of C, and impress your interviewer with your understanding of the fundamentals. Our blog is a perfect resource for anyone looking to take their C programming skills to the next level.

C Programming Interview Questions with Answers

Now, Let’s learn and get ready to impress!

1. Why is C called a mid-level Programming language?


C possesses traits from both lower-level (assembly level) and higher-level (higher level) languages. C is hence frequently referred to as a middle-level language. A user can write an operating system and a consumer billing system in C using the language.

2. What is a token?


In a program, the elements that exist individually are called tokens for eg:Identifiers, Keywords, Constants etc.

3. Use of printf() and scanf() function in C?


The use of printf() function is to print the output on the screen of the user it can be used to print string variables or any message of your choice. The use of scanf() function is to take the input from the user or read the input from the user.

4. What are format specifiers in C?


Format specifiers or data type specifier are used with printf and scanf functions to specify the type of data one needs to input from the user or output on the screen.

5. What is the built-in function in C?


Built-in functions are the functions that are present in the library of the language to make the life of the developer easier some of the common built-in functions are printf(), scanf().

6. What is a preprocessor?


A preprocessor is software that processes the information before compiling it. Inclusion of header files macros everything is possible because of the preprocessor.

7. How can a string be converted to a number?


The atoi method is used to convert a string to a number basically it converts the alphabet to the number and if we loop through the string the whole string Is converted.

8. What is recursion in C?


Recursion is when a function calls itself such a function is called a recursive function.

9. What is the difference between global int and static int declaration?


This is where it differs from that—in scope. A variable that is genuinely global has a global scope and is visible throughout your program.

Everything in your program can see the global variable global temp, but if you have a multi-file project, you’ll need to add a “extern int global temp;” to other source files to make it visible in other modules.

Although a static variable’s variables are not allocated in the memory’s stack segment, it has a local scope. Although it sits in the.bss segment of your built binary, like global variables, it can have scope that is not global.

10. What is a pointer in C?


A pointer is a variable type that points to the address of another variable.

11. Why n++ executes faster than n+1?


n++ being a unary operation, it just needs one variable. Whereas, n = n + 1 is a binary operation that adds overhead to take more time (also binary operation: n += 1).

12. What is typecasting in C?


Typecasting is a method to convert one variable datatype into another Syntax: data_type(expression).

13. What are the advantages of Macro over function?


Macro on an advanced copy-paste, its definitions to locations wherever it is invoked Because the control is always with the callee function, it saves a lot of time since it is never sent to a new function. One drawback is that the compiled binary is huge in size, but the programme comparatively runs faster once it has been compiled.

14. What are enumerations?


Enumeration is a user-defined data type also known as Enum in C. It has integers or constant integrals that have names assigned to them by the user.

15. When should we use the register storage specifier?


If a variable is often used, it should be defined using the register storage specifier; the compiler may then allocate a CPU register for the variable’s storage to facilitate variable search.

16. What are decision control statements in C?


Decision control statements are used to change the flow of the program by transferring control in the code using some conditions for eg: if else, switch case statement etc.

17. Difference between malloc() and calloc()?


The memory dynamic memory allocating routines calloc() and malloc(). The primary distinction is that calloc() requires two inputs, the number of blocks and the size of each block, whereas malloc() only accepts one argument, the number of bytes.

18. What is the difference between struct and union in C?


A struct is a collection of intricate data structures that are kept together in memory and given independent memory locations so that they can all be accessed simultaneously.

In contrast, all of the member variables in a union are kept in the same location in memory, which means that changing the value of one member would also modify the values of all the other members.

19. What is call by reference in functions?


When the function is called by actually passing the address of the parameter it is called pass by reference. The operations performed on the formal parameters affect the actual parameters.

20. What is dynamic memory allocation in C? Name the dynamic memory allocation functions.


Dynamic memory allocation is the method in which the memory is allocated in the heap and not in the stack the dynamic memory allocation functions that are present are calloc(), malloc(), free() and realloc().

21. What is the difference between #include “…” and #include <…>?


The place where the preprocessor looks for the included file actually differs in practise.
The C preprocessor initially checks the predefined list of system directories for the filename for #include filename> before checking the user-specified directories (we can use -I option to add directories to the mentioned predefined list).

The preprocessor searches for #include “filename” in the same directory as the file containing the directive first, then uses the same search path as for the #include filename> form. This approach is typically used to include header files that are defined by programmes.

22. What is the difference between ‘g’ and “g” in C?


The g with the double quotes refer to string in C whereas the g with the single quotes refer to a character in C also the strings end with a null terminator making it a 2-character array.

23. Can we compile a program without the main function in C?


Yes we can compile a program in C without using the main function with the help of macros

define xyz main
int xyz ()
printf(“Hello “);
return 0;

24. What is null pointer in C?


In the C programming language, a null pointer is a pointer that does not point to any memory location and hence does not hold the address of any variables.

25. What is the use of #define in C?


It specifies an identification and a string of characters that will be used in place of the identifier whenever it appears in the source file. The replacement procedure is known as a macro replacement, and the identification is known as a macro name.

26. What are entry control and exit control loops in C?


Entry control loop are two in C one is the for loop and one is the while loop whereas the exit control loop is the do while loop

27. Do all character arrays end with “nul”() character in C?


Only string are special character arrays that are null-terminated all the character arrays are not null-terminated.

28. What are the different ways to access structure members in C?


There are two ways in which we can access the structure members they are respectively the (.) operator and the (->) operator

29. What are the advantages and disadvantages of storing data in the heap area?


Comparatively speaking, heap storage is slower than stack storage. The versatility offered by the heap area is the key benefit. Any particular order can be used to allocate and deallocate memory in the heap region.

30. State different storage class specifiers?


  1. auto
  2. register
  3. extern
  4. static


This is an ultimate list of the 30 most asked C Programming interview questions. We also provided the answers to help you learn and crack software development interviews for freshers as well as intermediate-level candidates. Hope this article will help to face and crack any interview related to software development.

3 thoughts on “Top 30 C Programming Interview Questions with Answers”

Leave a Comment