operators - Write C statement that clears two bits without disturbing the other bits -

my assignment write 1 or more c statements clears (i.e. sets 0) bits 11 , 12 of variable "x" without disturbing other bits using bit-level c-operators. professor says: "the variable "mask", declared below, may helpful."

int mask = 0x00001800;  int x = arbitrary_value; 

should using shift operations combined bit-level operations? i'm bit unclear how make happen.

@garrett, force or mask values use bitwise operands (&, |, ~, ^). how you. can create mask, 1 created 0x00001800. if convert mask binary this: ‭1100000000000‬. can see starting right bits 11 , 12 ones stay high.

now, use mask mask value need know want do. case want force bits 11 , 12 of variable 0, so, force 0 can use , bitwise operand (&) passing 0 want force 0 , 1 want stay how on other variable. if want use mask 0x1800 operation must first invert bits, because want 0s right mask has 1s , 1s right has 0s. invert bits can use not bitwise operand, like:

int mask = 0x1800; int invertedmask = ~mask; 

value of variables in binary:

mask = 1100000000000 invertedmask = 0011111111111

now can force bits 11 , 12 variable zero, example:

int mask = 0x1800; //value in binary 1100000000000 int value = ‭7347‬;   //value in binary 1110010110011 int finalvalue = 0;  mask = ~mask; // mask value 0011111111111 finalvalue = value&mask; //final value 0010010110011 

as can see, bits 11 , 12 (from right left) forced down while other stay right in value variable.

and using principles can use lot of other combination, including shift of bits deslocate bits of mask example.