First remember that machine words are of fixed size. Say 4, and that your input is: Then pushing everything one position to the left gives: Question what to put as X? with a shift put 0 with rotate put a Now push everything one position to the right gives: Question what to put as X? … Read more
Shifting a number n bits left multiples the number by 2n. For example n << 3 = n*2³ = n*8. The corresponding instruction is To multiply any number you can split the number into sums of power of 2s. For example: n*10 = n*8 + n*2 = (n << 3) + (n << 1) SLL … Read more
According to K&R 2nd edition the results are implementation-dependent for right shifts of signed values. Wikipedia says that C/C++ ‘usually’ implements an arithmetic shift on signed values. Basically you need to either test your compiler or not rely on it. My VS2008 help for the current MS C++ compiler says that their compiler does an arithmetic shift.
The bit shifting operators do exactly what their name implies. They shift bits. Here’s a brief (or not-so-brief) introduction to the different shift operators. The Operators >> is the arithmetic (or signed) right shift operator. >>> is the logical (or unsigned) right shift operator. << is the left shift operator, and meets the needs of … Read more