What is the best way to set a particular bit in a variable in C

Question

Consider a variable unsigned int a; in C.

Now say I want to set any i\'th bit in this variable to \'1\'.

Note that the variable has some value.

Answer 1

Some useful bit manipulation macros

#define BIT_MASK(bit)             (1 << (bit))
#define SET_BIT(value,bit)        ((value) |= BIT_MASK(bit))
#define CLEAR_BIT(value,bit)      ((value) &= ~BIT_MASK(bit))
#define TEST_BIT(value,bit)       (((value) & BIT_MASK(bit)) ? 1 : 0)