# Toggle all the bits of a number except k-th bit.

Given a positive (or unsigned) integer **n**, write a function to toggle all the bits except k-th bit. Here value of k starts from 0 (zero) and from right.

Examples:

Input : n = 4294967295, k = 0 Output : 1 The number 4294967295 in 32 bits has all bits set. When we toggle all bits except last bit, we get 1. Input : n = 1, k = 1 Output : 4294967292 4294967262 has all bits toggled except second bit from right.

- Toggle bit at k-th position. We do it by finding a number with only k-th bit set (using 1 << k), then doing bitwise XOR of this number n.
- Toggle all bits of number obtained above using ~ (Bitwise negation)

`// C program to toggle all bits except kth bit ` `#include<stdio.h> ` ` ` `// Returns a number with all bit toggled in n ` `// except k-th bit ` `unsigned ` `int` `toggleAllExceptK(unsigned ` `int` `n, ` ` ` `unsigned ` `int` `k) ` `{ ` ` ` `/* 1) Toggle k-th bit by doing n ^ (1 << k) ` ` ` `2) Toggle all bits of the modified number */` ` ` `return` `~(n ^ (1 << k)); ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `unsigned ` `int` `n = 4294967295; ` ` ` `unsigned ` `int` `k = 0; ` ` ` `printf` `(` `"%u"` `, toggleAllExceptK( n, k)); ` ` ` `return` `0; ` `} ` |

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Output:

1

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