How does bitshift work?

bitshift(56,-1)
gives answer 28 in matlab
My understanding of this working is as follows:
the function converts 56 to binary value ie 0101 0110 and does right shift since its -1
so 0010 1011 -> 2b (hexa)
so the answer should be "2b" right?
How does this function work?

4 个评论

In your example, k = -1, so the shift is to the right, not the left.
"the function converts 56 to binary value ie 0101 0110"
You appear to have mixed up decimal and hexadecimal:
B = '01010110'; % your binary string
D = pow2(numel(B)-1:-1:0)*sscanf(B,'%1d') % decimal
D = 86
D = bin2dec(B) % decimal
D = 86
H = dec2hex(D) % hexadecimal
H = '56'
H = sprintf('%x',D) % hexadecimal
H = '56'

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 采纳的回答

dec2bin(56,8)
ans = '00111000'
In other words, your difficulty is that 0101 0110 is not the correct representation for 56.

3 个评论

So, 56 in binary is 00111000
May I know the conversion logic behind this
Consider for a moment that 56 decimal can be divided by 2 to get 28, and then divided by 2 again to get 14, and then divided by 2 again to get 7, but that cannot be divided by 2. That is three divisions, so the binary representation must end in three 0's.
It's also worth noting that with each division-by-two the remainder (0 or 1) becomes part of the binary result. The first remainder is the bit on the right (the least-significant bit). Each successive remainder is appended on the left. The following figure might help. It shows the conversion from decimal 26 to the binary equivalent, 11010.

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