Bitwise Operators are mainly used in low-level programming. Using the bit-wise operators we can set bit, check bit, clear or toggle the bits of an integral type. In the embedded system, a bit-wise operator performs the bit-wise operation on an individual bit of a PORT or Register.

Note: Quiz on bit-wise operators.

Note: Here I assume that bit of register starts with 0th position, it means the 2nd position is actually the 3rd bit.

Setting N-th Bit

Setting an N-th bit means that if the N-th bit is 0, then set it to 1 and if it is 1 then leave it unchanged. In C, bitwise OR operator (|) used to set a bit of integral data type. As we know that | (Bitwise OR operator) evaluates a new integral value in which each bit position is 1 only when operand’s (integer type) has a 1 in that position.

In simple words, you can say that “Bitwise OR ” of two bits is always one if any one of them is one.

That means,

0 | 0 = 0
1 | 0 = 1
0 | 1 = 1
1 | 1 = 1

Algorithm to set the bits:

Number | = (1UL << nth Position);

Method1: Set nth- bit in C using the function:

#include <stdio.h>

//function to set bit
int setBit(unsigned int data,unsigned int pos)
{
    return (data|(1 << pos));
}

int main()
{
    unsigned int cData=0x00;
    unsigned int pos =0;

    printf("cData = 0x%x\n\n",cData);

    //Get position from the user
    printf("Enter the position which you want set = ");
    scanf("%u",&pos);

    //Call function to set the bit
    cData = setBit(cData,pos);

    //Print the data
    printf("\n\n%dth Bit Set Now cData will be = 0x%x\n",pos,cData);

    return 0;
}

OutPut:

Explanation:

0 is represented as 0 in binary and has its D2 bit(third bit) 0, so setting it will result in 100 i.e. 4.

Method2: Set nth- bit in C using macro

#include <stdio.h>

//Macro to set nth-bit
#define SET_BIT(value, pos) (value |= (1U<< pos))


int main()
{
    //value
    unsigned int value =0;

    //bit position
    unsigned int pos = 0;


    printf("Enter the value = ");
    scanf("%u",&value);

    printf("Enter the position you want to Set = ");
    scanf("%u",&pos);

    //Calling Macro to set nth-bit
    printf("After setting nth-bit value will be = %d\n",SET_BIT(value,pos));

    return 0;
}

OutPut: 

Enter the value = 5
Enter the position you want to Set = 0
After setting nth-bit value will be = 5

Explanation:
5 is represented as 101 in binary and has its first bit 1. So after setting the 0th position, it will result in 101 i.e. 5.

Clearing a Bit

Clearing a bit means that if N-th bit is 1, then clear it to 0 and if it is 0 then leave it unchanged. Bitwise AND operator (&) use to clear a bit of integral data type. “AND” of two bits is always zero if any one of them is zero.

That means,
0 & 0 = 0
1 & 0 = 0
0 & 1 = 0
1 & 1 = 1

Algorithm to clear the bit:

To clear the nth bit, first, you need to invert the string of bits then AND it with the number.

Number  &=  ~(1UL << nth Position);

Method1: Clear nth- bit in C using the function:

#include <stdio.h>

//function to clear nth-bit
int clearNthBit(unsigned int data,unsigned int pos)
{
    return (data & (~(1 << pos)));
}
int main()
{
    unsigned int cData=0xFF;
    unsigned int pos =0;

    printf("Initially cData = 0x%x\n\n",cData);

    printf("Enter the position which you want clear = ");
    scanf("%u",&pos);

    //clear the nth bit.
    cData = clearNthBit(cData,pos);

    //Print the data
    printf("\n\n%uth Bit clear Now cData will be = 0x%x\n",pos,cData);

    return 0;
}

OutPut:

Explanation:

Clearing of D1 bit of 0XFF will give 0XFD.

Method2: Clear nth- bit in C using the macro:

#include <stdio.h>

//Macro to clear nth-bit
#define CLEAR_BIT(value, pos) (value &= (~(1U<< pos)))

int main()
{
    unsigned int cData=0xFF;
    unsigned int pos =0;

    printf("Initially cData = 0x%x\n\n",cData);

    printf("Enter the position which you want clear = ");
    scanf("%u",&pos);

    //Calling macro to clear nth-bit
    printf("After clearing nth-bit cData will be = 0x%x\n",CLEAR_BIT(cData,pos));

    return 0;
}

Output:

Initially cData = 0xff
Enter the position which you want clear = 0
After clearing nth-bit cData will be = 0xfe

Checking a Bit

To check the nth bit, shift the ‘1’ nth position toward the left and then “AND” it with the number.

An algorithm to check the bit

Bit = Number & (1UL << nth)

Method1: Check nth- bit in C using the function

#include <stdio.h>

#define SET     1
#define NOT_SET 0


//function to check nth bit
int isNthBitSet(unsigned int data,unsigned int pos)
{
    return ((data & (1 << pos))? SET : NOT_SET);
}


int main()
{
    //Given data
    unsigned int cData=0xFc;
    unsigned int pos =0;
    unsigned int isBitSet = 0;

    printf("Initially cData = 0x%x\n\n",cData);

    printf("Enter the position which you want check = ");
    scanf("%u",&pos);

    //Check bit set or not
    isBitSet  = isNthBitSet(cData,pos);

    if(isBitSet)
    {
        printf("\nBit is One\n");
    }
    else
    {
        printf("\nBit is zero\n");
    }

    return 0;
}

OutPut 1:

OutPut 2:

Method2: Check nth- bit in C using macro

#include <stdio.h>

//Macro to check nth-bit
#define IS_BIT_SET(value, pos) (value & (1U<< pos))


int main()
{
    //Given data
    unsigned int cData=0xFc;
    unsigned int pos =0;

    printf("Initially cData = 0x%x\n\n",cData);
    
    printf("Enter the position which you want check = ");
    scanf("%u",&pos);

    //Macro to check nth bit
    if(IS_BIT_SET(cData,pos))
    {
        printf("\n\nBit is One");
    }
    else
    {
        printf("\n\nBit is zero");
    }

    return 0;
}

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Toggling a Bit

Toggling a bit means that if the N-th bit is 1, then change it to 0 and if it is 0 then change it to 1. Bitwise XOR (^) operator used to toggle the bit of an integral data type. To toggle the nth bit shift the ‘1’ nth position toward the left and “XOR” it.

That means,
0 ^ 0 = 0
1 ^ 0 = 1
0 ^ 1 = 1
1 ^ 1 = 0

An algorithm to toggle the bits

Number  ^=  (1UL << nth Position);

A simple program to toggle a bit

#include <stdio.h>
#include <stdlib.h>


int main()
{

    unsigned int cData=0xF8;
    int pos =0;

    system("COLOR F");
    printf("Initially cData = 0x%x\n\n",cData);

    printf("Enter the position which you want toggle = ");
    scanf("%u",&pos);

    //toggle the nth bit.
    cData^=1<<pos;

    //Print the data
    printf("\n\n%uth Bit Set Now cData will be = 0x%x\n",pos,cData);

    return 0;
}

Output:

OutPut 2:

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Your opinion matters

Although here I have tried to puts a lot of points regarding the bit operators but I want to know your opinion on the binary operators, so please don’t forget to write a comment in the comment box.