c / c ++ bit arithmetic function

// a reversed, the i-th bit. 
// Obviously, a type of char, etc. can also be replaced. 

void flipBit ( int & a, int i) 
{ 
　　a ^ = ( . 1 << i); 
} 

// Get a first i.
int GETBIT ( int a, int i) 
{ 
　　return (i >> a) & . 1 ; 
} 

// set in a bit i.

void setBit(int & a,int i,int value) { if(value) a|=(1<<i); else a&=~(1<<i); }