# Swift - 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 16 50 -> 110010 (In Binary) | 25 -> | 011001 (In Binary) ---- -------- 59 <- 111011 (In Binary)

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

var x = 50 var y = 25 //Bitwise OR and assignment operation x |= y //Displaying the result print("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.

func MaxPowerOfTwo(_ N: Int) -> Int { var n = 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 } print("MaxPowerOfTwo(100) = ", MaxPowerOfTwo(100)) print("MaxPowerOfTwo(500) = ", MaxPowerOfTwo(500)) print("MaxPowerOfTwo(1000) = ", MaxPowerOfTwo(1000))

The above code will give the following output:

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

❮ Swift - Operators