Ruby - left shift operator
The Bitwise left shift operator (<<) takes the two numbers and left shift the bits of first operand by number of place specified by second operand. For example: for left shifting the bits of x by y places, the expression (x<<y) can be used. It is equivalent to multiplying x by 2y.
The example below describes how left shift operator works:
1000 << 2 returns 4000 (In Binary) 1000 -> 1111101000 << 2 | left shift the bits ----- V by 2 places 4000 <- 111110100000 (In Binary)
The code of using left shift operator (<<) is given below:
x = 1000 #left shift operation z = x << 2 #Displaying the result puts "z = #{z}"
The output of the above code will be:
z = 4000
Example: Count number of 1 Bits in a positive integer
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
Bitwise AND operation with 1 at any bit results into 1 if the bit is 1 or 0 if the bit is 0. Performing such operation at every bit, and counting the number of 1 gives the count of 1 bits in the given positive integer. To achieve this bitwise left shift operator can be used as shown in the example below:
def CountOneBits(n) mask = 1 count = 0 #performing bitwise AND operation #at every bit of the number for i in 0..31 if((mask & n) == mask) count += 1 end mask = mask << 1 end return count end puts "CountOneBits(1000) = #{CountOneBits(1000)}" puts "CountOneBits(1023) = #{CountOneBits(1023)}"
The above code will give the following output:
CountOneBits(1000) = 6 CountOneBits(1023) = 10
❮ Ruby - Operators