How to swap nibbles in C?

Question

How to swap the nibble bit positions of a number?

For example: 534, convert it into binary, the rightmost 4 bits has to be interchanged with the leftmost 4 bits and

Answer 1

1)

y = ((x >> 4) & 0x0f) | ((x << 4) & 0xf0);

2)

unsigned char swap_nibbles(unsigned char c)
{
     unsigned char temp1, temp2;

     temp1 = c & 0x0F;
     temp2 = c & 0xF0;
     temp1=temp1 << 4;
     temp2=temp2 >> 4;

     return(temp2|temp1); //adding the bits
}

3)

unsigned char nibbleSwap(unsigned char a)
{
    return (a<<4) | (a>>4);
}