CodeSubmit Interview Series

The 9 Best C Interview Questions in 2023

What are the top C interview questions? Today, you’ll get the best questions to ask at your next interview. Want to learn more? Read on!

Interviewing C developers 

C is a general-purpose language that is one of the most influential languages today. The language is often used in operating systems, device drivers, and protocol stacks. It’s often used in computer architecture–from supercomputers to microcontrollers and embedded systems. 

C is an imperative procedural language supporting structured programming, lexical variable scope, and recursion. It has a static type of system. C was created to encourage cross-platform programming and to be compiled to provide low-level memory and language constructs that efficiently map machine instructions. 

How do you identify the top C developers? That’s what we’ll look at next. 

Beginner C interview questions

What are the top C interview questions for junior developers? That’s what this chapter is all about. 

1. Explain the main features of C.   


C is a simple and efficient language that is portable and machine independent. This is a structured and mid-level language with a function-right library. C also includes Dynamic Memory Management, and it is very fast. 

2. Explain how functions are used in C.  


Functions are used in C to avoid the rewriting of the same code over and over. They can be called an infinite number of times from any place in the program. What’s more, if a program is divided into functions, any part of the program can be tracked. C provides the reusability concept and breaks the big task into smaller tasks so that it makes the C program more understandable.

3. Define static memory allocation. 


Memory is allocated at compile time, and it can’t increase while the program is being executed. Static memory allocation is used in the array. 

In static memory, the lifetime of a variable equals the lifetime of a program. Static memory is allocated with static keywords and implemented with stacks or heap. The pointer is needed to access the variable that is present in the static memory.

Ultimately, static memory is faster than dynamic memory, but more memory space is needed to store the variable.

4. Define dynamic memory allocation. 


Dynamic memory allocation is allocated at runtime. The memory can be increased while the program is executed. Dynamic memory allocation is used in the linked list. 

Memory must be allocated at the runtime using the malloc() or calloc() functions. Allocation or deallocation of memory is done at the execution time of a program. 

Dynamic pointers aren’t required to access the memory and it’s implemented using data segments. Dynamic memory allocation requires less memory space. 

5. Explain functions and their types. 


Functions are blocks of code that are used to perform a task many times over instead of writing it out many times in a program. Functions avoid the repetition of code and improve the readability of a program. They also make it easier to modify a program and so the risk of errors is reduced. 

The two types of functions are: 

User-defined functions

These are functions that are defined in order to reduce the complexity of bigger programs. They are essentially tailor-made functions, and their objective is to satisfy the condition where you are facing issues. 

Built-in functions

Library functions are provided by the compiler package. These consist of special functions with various meanings. You can directly use them without defining them. 

Senior C interview questions

What are the top C interview questions for senior developers? Here you go!

6. Does C support function overloading? 


No, C doesn’t support function overloading. When you compile the C source, the symbol needs to be intact in the object code. With function overloading in the source, you should also provide name mangling as a preventive measure to avoid name clashes. C is also not a strictly typed language, so many things are convertible to each other in C. In other words, the complexity of overload resolution could introduce confusion in a language like C. 

7. What are different types of decision control statements?


Every statement that is written in a program is executed from top to bottom. Control statements are used to execute and transfer the control from one part of the program to another, depending on conditions.

The different types of decision control statements are: 

  • If-else statement 
    • Normal if-else statement
    • Else-if statement
    • Nested if-else statement
  • Switch statement 

8. Should you use gets()? 


Using gets() is usually a bad idea. The reason is that the standard input library gets() reads user input until it encounters a new line character. But it doesn’t check for the size of the variable that is provided. The system is therefore vulnerable to buffer overflow and that input is written into memory where it isn’t supposed to. Gets() is used to achieve the same without a restricted range of input. 

9. Define a token.


A token is an identifier. It can be a keyword, string literal, constant, and so on. It’s the smallest individual unit in a program. C includes these tokens: 

  • Identifiers: These refer to the name of the variables
  • Keywords: Keywords are predefined words that are explained by a compiler 
  • Operators: Operators are symbols that perform specific operations
  • Constants: These are fixed values that can’t be changed during the execution of a program 
  • Special characters: Characters except for alphabets and digits are special characters

Over to you!

There you have it!

Now you know what the top C interview questions are. 

However, while interview questions are important, they’re not the only thing you need to include in your interview process to identify the right candidates.

Skill assessment tests are equally important. With skill assessment tools, you can easily and efficiently understand the level of your candidates’ skills. 

And that’s what CodeSubmit helps you do. CodeSubmit offers skill assessment and live coding tests to help you choose the top talent. 

Want to learn more? 

Try CodeSubmit for free (no credit card required).