Nibble Swapping in C (Hexadecimal Input) in C

January 03, 2026

C Program to Check Prime Number Using Efficient Logic

Introduction A prime number is a number that has exactly two distinct positive divisors: 1 and itself. In this program, we check whether a given number is prime or not using a simple and efficient logic. This type of program is commonly used in mathematics, competitive programming, and basic algorithm learning for beginners in C programming. Problem Statement The task is to write a C program that determines whether a given integer is a prime number or not. The program takes a single integer input from the user and analyzes its divisibility. If the number has no divisors other than 1 and itself, it should be identified as a prime number; otherwise, it is not prime. This problem is important in number theory and has practical relevance in areas such as cryptography, data validation, and algorithm design. Algorithm / Logic Explanation To check whether a number is prime, we need to verify that it is not divisible by any number other than 1 and itself. The algorithm follows a si...

🔶 Nibble Swapping in C (Hexadecimal Input)

#include<stdio.h> int main( ) { unsigned int num; printf("Enter the number(in hex):"); scanf("%x",&num); num = num & 0xFF; unsigned int swapped = ((num & 0x0F) << 4) | ((num & 0xF0) >> 4); printf("After swapping number is: %02X\\n", swapped); return 0; }

📘 Explanation:

This C program swaps the upper and lower 4-bit nibbles of an 8-bit hexadecimal number.

🔹 `scanf("%x", &num);` reads a hexadecimal value.
🔹 `num & 0xFF` ensures the value is within 8 bits.
🔹 `(num & 0x0F) << 4` moves the lower nibble to the upper nibble position.
🔹 `(num & 0xF0) >> 4` moves the upper nibble to the lower nibble position.
🔹 The final result is obtained by combining both using bitwise OR (`|`).
🔹 `%02X` prints the swapped result in uppercase hexadecimal format with leading zero if needed.

🔍 Sample Output:

Enter the number(in hex):3C
After swapping number is: C3

Enter the number(in hex):F0
After swapping number is: 0F

🏷️ Keywords:

bitwise operations in C, swap nibbles C, C program hex input, 8-bit nibble swap, binary logic in C, nibble masking, hex manipulation

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C Program to Check Prime Number Using Efficient Logic