Dharani Tech Edu Hub

Common Interview Questions in C

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Introduction

C interview questions help you test your understanding of core programming concepts.

👉 These questions are commonly asked in placements and technical interviews.

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Why Practice Interview Questions?

• ✔ Improve problem-solving
• ✔ Strengthen concepts
• ✔ Prepare for placements
• ✔ Build confidence

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1. What is the difference between ++i and i++?

Answer:

• ++i → Pre-increment (increase first, then use)
• i++ → Post-increment (use first, then increase)

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Example

#include <stdio.h>

int main() {
    int i = 5;

    printf("%d\n", ++i);
    printf("%d\n", i++);

    return 0;
}

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Output

6
6

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2. What is a Pointer?

Answer:

👉 A pointer is a variable that stores the address of another variable.

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3. What is the difference between Structure and Union?

Answer:

• Structure → Separate memory for each member
• Union → Shared memory

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4. What is NULL pointer?

Answer:

👉 A pointer that does not point to any valid memory location.

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5. What is Dangling Pointer?

Answer:

👉 A pointer pointing to memory that has been deallocated, freed, or gone out of scope.

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6. What is Memory Leak?

Answer:

👉 Memory allocated but not freed using free().

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7. What is Recursion?

Answer:

👉 A function calling itself.

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8. Difference between malloc() and calloc()?

Answer:

• malloc() → Uninitialized memory
• calloc() → Initialized to zero

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9. What is a Segmentation Fault?

Answer:

👉 Error caused by accessing invalid memory.

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10. What is static keyword?

Answer:

👉 Retains variable value between function calls.

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Interview Questions Table

Question	Key Concept
Increment Operators	Operators
Pointers	Memory
Structures vs Union	Data Types
Memory Leak	DMA
Recursion	Functions

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Important Notes

• Focus on concepts
• Practice coding questions
• Understand memory

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Common Mistakes

• ❌ Memorizing without understanding
• ❌ Ignoring basics
• ❌ Not practicing coding

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Pro Tips

• ✔ Revise fundamentals
• ✔ Practice daily
• ✔ Solve previous questions
• ✔ Explain answers clearly

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Conclusion

Interview questions in C help you prepare for technical rounds and improve your understanding of core concepts.

Practice regularly to succeed in interviews.

👉 This article is part of Dharani Tech Edu Hub — where learning programming is made simple and practical.