Bitwise operation and usage

Question

Consider this code:

x = 1        # 0001
x << 2       # Shift left 2 bits: 0100
# Result: 4

x | 2        # Bitwise OR: 0011
# Result: 3

x & 1              


        

Answer 1

One typical usage:

| is used to set a certain bit to 1

& is used to test or clear a certain bit

• Set a bit (where n is the bit number, and 0 is the least significant bit):

  unsigned char a |= (1 << n);

• Clear a bit:

  unsigned char b &= ~(1 << n);

• Toggle a bit:

  unsigned char c ^= (1 << n);

• Test a bit:

  unsigned char e = d & (1 << n);

Take the case of your list for example:

x | 2 is used to set bit 1 of x to 1

x & 1 is used to test if bit 0 of x is 1 or 0