C program to toggle or invert nth bit of a number

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C program to toggle or invert nth bit of a number

Write a C program to input any number from user and toggle or invert or flip nth bit of the given number using bitwise operator. How to toggle nth bit of a given number using bitwise operator in C programming. C program set nth bit of a given number if it is unset otherwise unset if it is set.

Required knowledge

Operators, Data Types in c, Variables in C, Basic input/output

Logic to toggle nth bit of a number

Toggling bit means setting a bit in its complement state. Means if bit is currently set then change it to unset and vice versa.

To toggle a bit we will use bitwise XOR ^ operator. Bitwise XOR operator evaluates to 1 if corresponding bit of both operands are different otherwise evaluates to 0. We will use this ability of bitwise XOR operator to toggle a bit. For example - if Least Significant Bit of num is 1, then num ^ 1 will make LSB of num to 0. And if LSB of num is 0, then num ^ 1 will toggle LSB to 1.

Step by step descriptive logic to toggle nth bit of a number.

1. Input number and nth bit position to toggle from user. Store it in some variable say num and n.

2. Left shift 1 to n times, i.e. 1 << n.

3. Perform bitwise XOR with num and result evaluated above i.e. num ^ (1 << n);.

Program to toggle or invert nth bit

/**
 * C program to toggle nth bit of a number
 */

#include <stdio.h>

int main()
{
    int num, n, newNum;

    /* Input number from user */
    printf("Enter any number: ");
    scanf("%d", &num);

    /* Input bit position you want to toggle */
    printf("Enter nth bit to toggle (0-31): ");
    scanf("%d", &n);

    /*
     * Left shifts 1, n times
     * then perform bitwise XOR with num
     */
    newNum = num ^ (1 << n);

    printf("Bit toggled successfully.\n\n");
    printf("Number before toggling %d bit: %d (in decimal)\n", n, num);
    printf("Number after toggling %d bit: %d (in decimal)\n", n, newNum);

    return 0;
}

Output:

Enter any number: 10
Enter nth bit to toggle (0-31): 20
Bit toggled successfully.

Number before toggling 20 bit: 10 (in decimal)
Number after toggling 20 bit: 1048586 (in decimal)

Process returned 0 (0x0)   execution time : 13.799 s

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