C Programming Codes

#CProgramming #Bitwise #OddEven

Odd or Even using Bitwise Operator

#include <stdio.h>

int main() {
    int num = 7;
    if (num & 1) {
        printf("%d is odd.\n", num);
    } else {
        printf("%d is even.\n", num);
    }
    return 0;
}

#CProgramming #SetBits #LookupTable

Count Set Bits using Lookup Table

#include <stdio.h>
#include <stdint.h>

unsigned char setBits[256] = {
    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};

int countSetBits(int n) {
    int count = 0;
    count += setBits[n & 0xFF];
    n >>= 8;
    count += setBits[n & 0xFF];
    n >>= 8;
    count += setBits[n & 0xFF];
    n >>= 8;
    count += setBits[n & 0xFF];
    return count;
}

int main() {
    int num = 0b10110011101011001101010111100010;
    printf("Number of set bits in %d is %d\n", num, countSetBits(num));
    return 0;
}

#CProgramming #BitManipulation #RightmostBit

Isolate Rightmost Set Bit

#include <stdio.h>

int isolateRightmostSetBit(int n) {
    return n & -n;
}

int main() {
    int num = 20; // Example number (binary 10100)
    int isolatedBit = isolateRightmostSetBit(num);
    printf("Original number: %d\n", num);
    printf("Rightmost set bit: %d\n", isolatedBit);
    return 0;
}

#CProgramming #BitwiseOperations #InterviewQuestion

Turn Off Rightmost Set Bit

#include <stdio.h>

int turnOffRightmostSetBit(int n) {
    return n & (n - 1);
}

int main() {
    int num = 12; 
    int result = turnOffRightmostSetBit(num);
    printf("Original number: %d\n", num);
    printf("Number with rightmost set bit turned off: %d\n", result);
    return 0;
}

#CProgramming #BitManipulation #RightmostBit

Find Position of Rightmost Set Bit

#include <stdio.h>

int findRightmostSetBit(unsigned int n) {
    if (n == 0) {
        return 0; 
    }
    int pos = 1;
    while ((n & 1) == 0) {
        n = n >> 1;
        pos++;
    }
    return pos;
}

int main() {
    unsigned int num = 12;  // Example number (1100 in binary)
    int position = findRightmostSetBit(num);
    printf("Rightmost set bit is at position: %d\n", position);
    return 0;
}

#CProgramming #BitManipulation #RightmostBit

Find Position of Rightmost Set Bit

#include <stdio.h>

int findRightmostSetBit(unsigned int n) {
    if (n == 0)
        return 0;
    int pos = 1;
    while ((n & 1) == 0) {
        n = n >> 1;
        pos++;
    }
    return pos;
}

int main() {
    unsigned int num = 12; // Example: 1100 in binary
    int position = findRightmostSetBit(num);
    printf("Rightmost set bit is at position: %d\n", position);
    return 0;
}

#CProgramming #BitManipulation

Check if Number has Only One Bit Set

#include <stdio.h>
#include <stdbool.h>

bool isOnlyOneBitSet(int n) {
    if (n <= 0) {
        return false;
    }
    return (n & (n - 1)) == 0;
}

int main() {
    int num = 8;
    if (isOnlyOneBitSet(num)) {
        printf("%d has only one bit set.\n", num);
    } else {
        printf("%d does not have only one bit set.\n", num);
    }
    return 0;
}

#CProgramming #BitwiseOperators #Optimization

Divide/Multiply by 2 using Bit Shift

#include <stdio.h>

int main() {
    int num = 16;
    int multiplyBy2 = num << 1;
    int divideBy2 = num >> 1;

    printf("Original number: %d\n", num);
    printf("Multiplied by 2: %d\n", multiplyBy2);
    printf("Divided by 2: %d\n", divideBy2);

    return 0;
}

#CProgramming #Bitwise #PowerOf2

Check if a Number is Power of 2

#include <stdio.h>
#include <stdbool.h>

bool isPowerOfTwo(int n) {
  if (n <= 0) {
    return false;
  }
  return (n & (n - 1)) == 0;
}

int main() {
  int num = 16;
  if (isPowerOfTwo(num)) {
    printf("%d is a power of 2\n", num);
  } else {
    printf("%d is not a power of 2\n", num);
  }
  return 0;
}

#CProgramming #Bitwise

Check if a Number is Power of 2

#include <stdio.h>#include <stdbool.h>bool isPowerOfTwo(int n) {    if (n <= 0) {        return false;    }    return (n & (n - 1)) == 0;}int main() {    int num = 16;    if (isPowerOfTwo(num)) {        printf("%d is a power of 2\n", num);    } else {        printf("%d is not a power of 2\n", num);    }    return 0;}