Comprehensive C Programming Interview Questions for Diploma Students

Basic Concepts

1. Syntax and Structure
   • What are the key components of a C program?
   • Explain the difference between #include<stdio.h> and #include<math.h>.
   • Why is the main() function important in a C program?
2. Data Types and Variables
   • What is the difference between a variable and a constant in C?
   • Name and explain different data types in C.
   • How do you declare a pointer? Give an example.
3. Operators
   • Explain the difference between = and ==.
   • What is the difference between pre-increment (++i) and post-increment (i++)?

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Control Statements

4. Conditional Statements
   • Write a C program to find the largest of three numbers using if-else.
   • How is a switch statement different from an if-else statement?
5. Loops
   • Write a program to print the first 10 Fibonacci numbers using a for loop.
   • Explain the difference between a while loop and a do-while loop.

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Functions

6. Basics of Functions
   • What is the difference between a function declaration and a function definition?
   • Write a function to calculate the factorial of a number.
7. Passing Parameters
   • What is the difference between passing parameters by value and by reference in C?

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Arrays and Strings

8. Arrays
   • Write a program to find the sum of all elements in an array.
   • Explain the difference between a one-dimensional and a two-dimensional array.
9. Strings
   • Write a program to check if a given string is a palindrome.
   • How are strings represented in C?

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Pointers

10. Basics of Pointers
    • What is a NULL pointer?
    • Write a program to swap two numbers using pointers.
11. Pointer and Array Relationship
    • Explain how pointers and arrays are related. Provide an example.

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Structures and File Handling

12. Structures
    • What is the purpose of using structures in C?
    • Write a program to create a structure for a student containing fields for name, roll number, and marks, and display the details.
13. File Handling
    • What is the difference between fopen and fclose?
    • Write a program to read data from a file and display it on the console.

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Advanced Topics

14. Dynamic Memory Allocation
    • Explain the difference between malloc and calloc.
    • Write a program to allocate memory dynamically for an array of integers.
15. Recursion
    • What is recursion? Write a program to calculate the GCD of two numbers using recursion.
16. Command-Line Arguments
    • What are command-line arguments in C? Write a simple program to demonstrate their usage.