C Language – 50 Q&A Practice
1. What is C language?
Answer: C is a general-purpose programming language developed by Dennis Ritchie in 1972.
Note: Used for system programming like OS and embedded systems.
2. Who developed C language?
Answer: Dennis Ritchie developed C at Bell Labs.
Note: He also contributed to UNIX.
3. What is the extension of C files?
Answer: .c
Note: Example: program.c
4. What is the entry point of a C program?
Answer: main() function.
Note: Every C program starts execution from main().
5. What is a variable?
Answer: A variable stores data in memory.
Note: Example: int a = 10;
6. What are data types in C?
Answer: int, float, char, double.
Note: They define the type of data stored.
7. What is printf()?
Answer: A function used to print output.
Note: Defined in stdio.h
8. What is scanf()?
Answer: Used to take input from the user.
Note: Example: scanf('%d', &a);
9. What is a pointer?
Answer: A variable that stores the address of another variable.
Note: Example: int *p;
10. What is an array?
Answer: A collection of elements of the same data type stored in contiguous memory.
Note: Example: int arr[5];
11. What is a function?
Answer: A block of code that performs a specific task and can be reused.
Note: Example: int add(int a, int b);
12. What is a loop?
Answer: A control structure that repeats a block of code multiple times.
Note: Types: for, while, do-while.
13. What is recursion?
Answer: A function calling itself.
Note: Example: factorial using recursion.
14. What is a structure?
Answer: A user-defined data type that groups variables of different types.
Note: Example: struct Student { int id; char name[20]; };
15. What is a union?
Answer: A user-defined data type where all members share the same memory location.
Note: Used for memory optimization.
16. What is a string in C?
Answer: A sequence of characters terminated by a null character.
Note: Example: char name[] = "Sunitha";
17. What is a header file?
Answer: A file that contains function declarations and macros.
Note: Example: stdio.h
18. What is a macro?
Answer: A fragment of code defined using #define.
Note: Example: #define PI 3.14
19. What is dynamic memory allocation?
Answer: Allocating memory during program execution.
Note: Functions: malloc(), calloc(), realloc(), free().
20. What is malloc()?
Answer: A function used to allocate memory dynamically.
Note: Example: ptr = (int*)malloc(sizeof(int));
21. What is calloc()?
Answer: Allocates memory and initializes it to zero.
Note: Example: ptr = (int*)calloc(5, sizeof(int));
22. What is realloc()?
Answer: Resizes previously allocated memory.
Note: Example: realloc(ptr,newsize);
23. What is free()?
Answer: Used to release dynamically allocated memory.
Note: Example: free(ptr);
24. What is file handling?
Answer: Reading and writing data to files.
Note: Functions: fopen(), fclose(), fprintf(), fscanf().
25. What is fopen()?
Answer: Opens a file.
Note: Example: fopen("file.txt","r");
26. What is fclose()?
Answer: Closes an opened file.
Note: Example: fclose(fp);
27. What is fprintf()?
Answer: Writes formatted output to a file.
Note: Similar to printf.
28. What is fscanf()?
Answer: Reads formatted input from a file.
Note: Similar to scanf.
29. What is a global variable?
Answer: A variable declared outside all functions.
Note: Accessible throughout the program.
30. What is a local variable?
Answer: A variable declared inside a function.
Note: Accessible only within that function.
31. What is a static variable?
Answer: A variable that retains its value between function calls.
Note: Declared using static keyword.
32. What is the sizeof operator?
Answer: Used to determine the size of a data type.
Note: Example: sizeof(int)
33. What is type casting?
Answer: Converting one data type into another.
Note: Example: (float)a
34. What is ASCII?
Answer: Character encoding standard.
Note: Example: ASCII value of A = 65
35. What is a compiler?
Answer: Software that converts C code into machine code.
Note: Example: GCC compiler.
36. What is debugging?
Answer: Process of finding and fixing errors.
Note: Helps improve program correctness.
37. What is an algorithm?
Answer: Step-by-step solution to a problem.
Note: Used before writing code.
38. What is a flowchart?
Answer: Graphical representation of an algorithm.
Note: Helps visualize logic.
39. What is a segmentation fault?
Answer: Error caused by invalid memory access.
Note: Often caused by incorrect pointers.
40. What is a dangling pointer?
Answer: Pointer pointing to freed memory.
Note: Dangerous in programs.
41. What is a null pointer?
Answer: Pointer that points to nothing.
Note: Example: int *ptr = NULL;
42. What is pointer arithmetic?
Answer: Operations performed on pointer variables.
Note: Example: ptr++
43. What is a command line argument?
Answer: Arguments passed to the program when executing.
Note: Example: int main(int argc, char *argv[])
44. What is the difference between call by value and call by reference?
Answer: Call by value passes a copy; call by reference passes address.
Note: Use & operator for reference.
45. What is an IDE?
Answer: Software used to write and run programs.
Note: Example: VS Code, CodeBlocks.
46. What is break?
Answer: Terminates a loop or switch.
Note: Used inside loops or switch statements.
47. What is continue?
Answer: Skips current iteration and continues the loop.
Note: Used inside loops.
48. What is a do-while loop?
Answer: Executes code at least once and then checks condition.
Note: Syntax: do { } while(condition);
49. What is a while loop?
Answer: Executes a block while condition is true.
Note: Syntax: while(condition) { }
50. What is a for loop?
Answer: Executes a block a known number of times.
Note: Syntax: for(initial; condition; increment) { }