Bit-Fields in C - Real World Example

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...

📌 Bit-Fields in C – Real World Example

🔋 1. Embedded System: Status Flags using Bit-Fields

#include <stdio.h>

struct StatusFlags {
    unsigned int powerOn : 1;
    unsigned int error : 1;
    unsigned int batteryLow : 1;
    unsigned int reserved : 5;
};

int main() {
    struct StatusFlags device = {1, 0, 1, 0};

    printf("Power ON: %u\n", device.powerOn);
    printf("Error: %u\n", device.error);
    printf("Battery Low: %u\n", device.batteryLow);

    return 0;
}

🧠 Explanation:

struct StatusFlags uses only 8 bits (1 byte) instead of 4 bytes.
Each flag (like power, error) is a bit-field that takes just 1 bit.
Perfect for embedded systems where memory and performance are critical.

🖥️ Sample Output:

Power ON: 1
Error: 0
Battery Low: 1

🔑 Keywords:

bit field in C, struct with bit-fields, embedded systems flags, memory-efficient C code, real-world struct usage, flag register, C interview examples

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C Program to Check Prime Number Using Efficient Logic