C Pointers Interview Questions 2026: 30 Q&A With Code

Last Updated: June 2026 | Level: Freshers to Mid-Level | Read Time: ~16 min

In C, pointers are everything: arrays, strings, dynamic memory, and callbacks all run through them. Candidates report that pointer arithmetic, the array-pointer relationship, and malloc/free are guaranteed for embedded and core-CS interviews. This guide covers 30 C pointer questions with full answers and predict-the-output traps. Behaviour reflects the official C language references; confirm any memory semantics on the standard.

Pair this with C Programming Placement Questions and C Output Prediction Questions 2026.

Table of Contents

1. Pointer Basics (Q1 to Q9)
2. Arrays and Strings (Q10 to Q18)
3. Dynamic Memory (Q19 to Q24)
4. Function Pointers and Advanced (Q25 to Q30)
5. Predict the Output
6. Quick Revision Table
7. Frequently Asked Questions

Pointer Basics

Q1. What is a pointer in C? Easy

int x = 10;
int *p = &x;
printf("%d", *p);   // 10

Q2. What is the size of a pointer? Medium

Q3. What is a null pointer? Easy

Q4. What is a dangling pointer? Medium

Q5. What is a wild pointer? Easy

Q6. What is pointer arithmetic? Medium

Q7. What is a void pointer and its limitation? Medium

Q8. What is the difference between *p++ and (*p)++? Hard

Q9. What is a double pointer? Medium

Arrays and Strings

Q10. What is the relationship between arrays and pointers? Medium

Q11. Why is sizeof(array) different from sizeof(pointer)? Hard

Q12. How are strings represented in C? Easy

Q13. What is the difference between char arr[] and char *p for strings? Hard

Q14. How do you pass an array to a function? Medium

void print(int *a, int n) {
  for (int i = 0; i < n; i++) printf("%d ", a[i]);
}

Q15. What is pointer to an array vs array of pointers? Hard

Q16. How do you iterate a string using pointers? Medium

char *s = "abc";
while (*s) { putchar(*s); s++; }

Q17. What does the array name evaluate to? Medium

Q18. Can you change where an array name points? Easy

Dynamic Memory

Q19. What are malloc, calloc, realloc, and free? Medium

Q20. What is the difference between malloc and calloc? Medium

Q21. What happens if you free the same pointer twice? Hard

Q22. What is a memory leak in C? Easy

Q23. Should you cast the result of malloc? Hard

Q24. What does realloc return on failure? Medium

Function Pointers and Advanced

Q25. What is a function pointer? Medium

int add(int a, int b) { return a + b; }
int (*fp)(int, int) = add;
printf("%d", fp(2, 3));   // 5

Q26. How is qsort implemented with function pointers? Hard

Q27. What is a pointer to a const vs a const pointer? Hard

Q28. What is the difference between pass by value and pass by pointer? Medium

Q29. How do you swap two integers using pointers? Medium

void swap(int *a, int *b) {
  int t = *a; *a = *b; *b = t;
}

Q30. What is the difference between stack and heap memory? Medium

Predict the Output

Snippet 1

int a[] = {1, 2, 3};
int *p = a;
printf("%d %d", *(p + 1), *p + 1);

Output:

2 2

Why: *(p+1) is the second element (2). *p + 1 is the first element (1) plus 1, also 2 here. Precedence trap that interviewers vary.

Snippet 2

char *s = "hello";
printf("%c", *(s + 1));
printf("%lu", sizeof(s));

Output:

e8

Why: *(s+1) is 'e'. sizeof(s) is the pointer size (8 on 64-bit), not the string length.

Snippet 3

int x = 5, *p = &x, **pp = &p;
**pp = 20;
printf("%d", x);

Output:

20

Why: Double dereference writes through pp to p to x, setting it to 20.

Quick Revision Table

Related Articles

• C Programming Placement Questions, the master set
• C Output Prediction Questions 2026, tricky snippets
• C++ Pointers Interview Questions 2026, pointers in C++
• Data Structures Interview Questions 2026, pointer-based structures

Confirm any pointer or memory semantics on the official C language references before your interview. This guide reflects candidate-reported patterns and public preparation resources as of June 2026.