Set individual bit in C++

Question

I have a 5 byte data element and I need some help in figuring out how in C++ to set an individual bit of one of these byte; Please see my sample code below:

Answer 1

Typically we set bits using bitwise operator OR (operator| or operator|= as a shorthand).

Assuming 8-bits to a byte (where the MSB is considered the '7st' bit and the LSB considered the 0th: MSB 0) for simplicity:

char some_char = 0;
some_char |= 1 << 0; // set the 7th bit (least significant bit)
some_char |= 1 << 1; // set the 6th bit
some_char |= 1 << 2; // set the 5th bit
// etc.

We can write a simple function:

void set_bit(char& ch, unsigned int pos)
{
    ch |= 1 << pos;
}

We can likewise test bits using operator&.

// If the 5th bit is set...
if (some_char & 1 << 2)
    ...

You should also consider std::bitset for this purpose which will make your life easier.