**Logic:
**A 64-bit integer can be viewed as an array of 64 bits, with the bit at index 0 corresponding to the least significant bit and the bit at index 63 corresponding to the most significant bit. For above problem, we have flip i

^{th}bit, i.e if i

^{th}bit is 0 then we have to change it to 1, and vice versa. For this, take a long integer 1, move it to i

^{th}position by left sifting, then xor with number.

**Program:**

<?php $a = 134 ; // original number $i = 3 ; //four bit index from zero $b = $a ^ (1 << $i ); printf("Original number : %b" , $a) ; printf(" After of %d bit number : %b" , $i, $b) ;

**Output:**

Original number : 10000110 After of 3 bit number : 10001110