bitwise operators - Java - Setting a distinct bit of an integer to zero -

here description:

in order stop mad coder evil genius need decipher encrypted message sent minions. message contains several numbers that, when typed supercomputer, launch missile sky blocking out sun, , making people on earth grumpy , sad.

you figured out numbers have modified single digit in binary representation. more specifically, in given number n kth bit right set 0, current value might different. it's write function change kth bit of n 0.

example

for n = 37 , k = 3, output should killkthbit(n, k) = 33.

3710 = 1001012 ~> 1000012 = 3310.

for n = 37 , k = 4, output should be

killkthbit(n, k) = 37.

the 4th bit 0 (looks mad coder forgot encrypt number), answer still 37."

here solution found , cannot understand it:

int killkthbit(int n, int k) {   return n & ~(1 << (k - 1)) ; } 

can explain solution , syntax?

detailed explanation of function

the expression 1 << (k - 1) shifts number 1 k-1 times left example 8 bit number , k = 4:

before shift: 00000001
after shift: 00010000

this marks bit kill. see, 1 shifted fourth position, on position zero. operator ~ negates each bit, meaning 1 becomes 0 , 0 becomes 1. our example:

before negation: 00010000
after negation: 11101111

at last, & executes bit-wise and on 2 operands. let say, have number n = 17, 00010001 in binary. our example is:

00010001 & 11101111 = 00000001

this is, because each bit of both numbers compared and on the same position. positions, both numbers have 1 remain 1, others set 0. consequently, position 0 remains 1.

overall method int killkthbit(int n, int k) binary operators, sets bit on position k of number n 0.

if want learn more topic, can refer documentation bitwise operators.