Interview Questions on Chapter 4: Functions in C

Here are 30 interview questions along with their answers on Chapter 4: Functions in C:

Chapter 4: Functions in C

1. What is a function in C?

• Answer: A function in C is a block of code that performs a specific task. It is a way to organize code into reusable blocks that can be called from other parts of the program.

2. What is the syntax of a function in C?

• Answer: The basic syntax of a function is:
  c return_type function_name(parameter_list) { // function body }

3. What is the difference between a function declaration and a function definition in C?

• Answer:
  • A function declaration (or prototype) specifies the function’s name, return type, and parameters but does not provide the body.
  • A function definition provides the actual code implementation of the function.

4. What are the types of functions in C?

• Answer: Functions in C can be classified as:
  • Library functions: Predefined functions like printf(), scanf().
  • User-defined functions: Functions defined by the programmer to perform specific tasks.

5. What is a return type in a function?

• Answer: The return type specifies the type of value the function will return. If the function does not return anything, the return type is void.

6. What are function parameters in C?

• Answer: Function parameters are the values passed to a function to allow it to operate. They are declared in the function signature and can be of any data type.

7. What is the purpose of the return statement in a function?

• Answer: The return statement is used to exit the function and optionally return a value to the calling function.

8. What is the scope of a function?

• Answer: The scope of a function refers to the region in the code where the function can be called. A function is accessible from anywhere in the program if it is declared or defined before use.

9. What is a void function in C?

• Answer: A void function is a function that does not return any value. Its return type is specified as void. Example:
  c void display() { printf("Hello, World!"); }

10. What is function overloading in C?

• Answer: C does not support function overloading directly. However, the concept involves using the same function name with different parameter types or numbers in other languages like C++.

11. What is recursion in C?

• Answer: Recursion is a process where a function calls itself. It is commonly used in problems like factorial calculation, tree traversal, and more.

12. What is the base case in recursion?

• Answer: The base case in recursion is a condition that stops the function from calling itself, preventing infinite recursion.

13. Can a function return a pointer in C?

• Answer: Yes, a function can return a pointer to a memory location, but care must be taken when dealing with memory management.

14. How do you pass an array to a function in C?

• Answer: In C, arrays are passed to functions by reference, meaning the function receives the address of the array rather than a copy of it.
  c void display(int arr[]) { // Function code }

15. What is a function prototype?

• Answer: A function prototype is a declaration of a function that specifies the function’s name, return type, and parameters. It is used to inform the compiler about the function before its actual definition.
  c int add(int, int); // Prototype

16. What is the difference between call by value and call by reference?

• Answer:
  • Call by value: The actual value of the argument is passed to the function, and changes to the parameter inside the function do not affect the original argument.
  • Call by reference: The address of the argument is passed, so changes to the parameter inside the function directly affect the original argument.

17. What are the advantages of using functions in C?

• Answer: Functions promote code reusability, modularity, and easier debugging. They also improve program readability and maintainability.

18. Can a function in C have no parameters?

• Answer: Yes, a function can have no parameters. The syntax would look like this:
  c void function_name(void) { // Code }

19. What is a function pointer in C?

• Answer: A function pointer is a pointer that points to a function instead of a data variable. It can be used to call a function indirectly.

20. What is the difference between exit() and return in functions?

• Answer:
  • exit() is used to terminate the program, regardless of where it is called.
  • return exits the function and optionally returns a value to the caller.

21. What is the purpose of the static keyword in a function?

• Answer: The static keyword in a function makes the function’s local variables persist between function calls. It prevents the variable from being reinitialized each time the function is called.

22. What is the difference between a local and a global function?

• Answer:
  • A local function is defined inside another function and is accessible only within that function.
  • A global function is defined outside of any function and can be accessed throughout the program.

23. What happens if a function does not have a return statement?

• Answer: If a function with a non-void return type does not have a return statement, the behavior is undefined, and it may lead to errors or unexpected results.

24. Can you call a function inside another function in C?

• Answer: Yes, you can call a function inside another function in C. This is a common practice to break complex tasks into smaller, more manageable pieces.

25. What is the difference between printf() and scanf()?

• Answer:
  • printf() is used to display output to the console.
  • scanf() is used to take input from the user.

26. What is a predefined function in C?

• Answer: A predefined function is a function that is already provided by the C standard library, such as printf(), scanf(), sqrt(), etc.

27. How do you handle multiple return statements in a function?

• Answer: You can have multiple return statements in a function. Depending on the condition, one of them will be executed, and the function will return a value at that point.

28. Can you pass a function as an argument to another function in C?

• Answer: Yes, you can pass a function as an argument by passing a function pointer to another function.

29. What is the significance of the void pointer in C functions?

• Answer: A void pointer is a generic pointer type that can point to any data type. It is often used when a function can accept different data types as arguments.

30. What is the significance of a recursive function?

• Answer: A recursive function is significant for solving problems that can be broken down into smaller subproblems of the same type. Examples include calculating factorials, solving Fibonacci sequences, and traversing data structures like trees.

These questions cover the key concepts of functions in C programming, focusing on function definition, declaration, recursion, scope, and function-related operations.