# Ruby - Bitwise OR and assignment operator

The Bitwise OR and assignment operator (|=) assigns the first operand a value equal to the result of Bitwise OR operation of two operands.

(x |= y) is equivalent to (x = x | y)

The Bitwise OR operator (|) is a binary operator which takes two bit patterns of equal length and performs the logical OR operation on each pair of corresponding bits. It returns 1 if either or both bits at the same position are 1, else returns 0.

Bit_1 | Bit_2 | Bit_1 | Bit_2 |
---|---|---|

0 | 0 | 0 |

1 | 0 | 1 |

0 | 1 | 1 |

1 | 1 | 1 |

The example below describes how bitwise OR operator works:

50 | 25 returns 59 50 -> 110010 (In Binary) | 25 -> | 011001 (In Binary) ---- -------- 59 <- 111011 (In Binary)

The code of using Bitwise OR operator (|) is given below:

x = 50 y = 25 #Bitwise OR and assignment operation x |= y #Displaying the result puts "x = #{x}"

The output of the above code will be:

x = 59

### Example: Find largest power of 2 less than or equal to given number

Consider an integer 1000. In the bit-wise format, it can be written as 1111101000. However, all bits are not written here. A complete representation will be 32 bit representation as given below:

00000000000000000000001111101000

Performing

00000000000000000000001111111111

Adding one to this result and then right shifting the result by one place will give largest power of 2 less than or equal to 1000.

00000000000000000000001000000000

The below code will calculate the largest power of 2 less than or equal to given number.

def MaxPowerOfTwo(n) #changing all right side bits to 1. n |= (n>>1) n |= (n>>2) n |= (n>>4) n |= (n>>8) n |= (n>>16) #adding 1 to n makes smallest power #of 2 greater than given number n += 1 #right shift by one position makes #largest power of 2 less than or #equal to given number n >>= 1 return n end puts "MaxPowerOfTwo(100) = #{MaxPowerOfTwo(100)}" puts "MaxPowerOfTwo(500) = #{MaxPowerOfTwo(500)}" puts "MaxPowerOfTwo(1000) = #{MaxPowerOfTwo(1000)}"

The above code will give the following output:

MaxPowerOfTwo(100) = 64 MaxPowerOfTwo(500) = 256 MaxPowerOfTwo(1000) = 512

❮ Ruby - Operators