2008年8月11日 · C, however, has only one right shift operator, >>. Many C compilers choose which right shift to perform depending on what type of integer is being shifted; often signed integers are shifted using the arithmetic shift, and unsigned integers are shifted using the logical shift. So it sounds like it depends on your compiler.

Also note that C and C++ do not distinguish between the right shift operators. They provide only the >> operator, and the right-shifting behavior is implementation defined for signed types. The rest of the answer uses the C# / Java operators. (In all mainstream C and C++ implementations including GCC and Clang/LLVM, >> on signed types is ...

2015年5月21日 · You don't shift 0 or 1, you shift the bit values, be it either 0 or 1. In other words, you Shift the bit positions, regardless of the value stored in them. From C11 standard, chapter §6.5.7. , Bitwise shift operators. The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are filled with zeros.

2011年6月17日 · Left shift: It is equal to the product of the value which has to be shifted and 2 raised to the power of number of bits to be shifted. Example: 1 << 3 0000 0001 ---> 1 Shift by 1 bit 0000 0010 ----> 2 which is equal to 1*2^1 Shift By 2 bits 0000 0100 ----> 4 which is equal to 1*2^2 Shift by 3 bits 0000 1000 ----> 8 which is equal to 1*2^3

2010年5月5日 · In C, there is no notion of the carry flag used by the assembly version in the register pair left shift. Instead, it is emulated, based on the observation that the result of an addition modulo 2 n can be smaller that either addend only if there was a carry out.

As of c++20 the bitwise shift operators for signed integers are well defined. The left shift a<<b is equivalent to a*2^b modulus 2^N where N is the number of bits in the resulting type. In particular 1<<31 is in fact the smallest int value. The right shift a>>b is …

2012年9月28日 · This is elementary, but my googling just doesn't cut it. I know I have to do something else to shift the values of an array one by one, but the below coding gives me the same values for items[k] to items[infinity] all equaling items[k]. What I don't understand is how to preserve the original k+1 value while I copy the k value into the k+1 slot.

2011年12月7日 · In the 2023 Korean regional government 9th hiring test, it asked what the result will be if you right-shift a signed binary 10110101 by 2 bits in C. It had both (1) 00101101 and (4) 11101101 in the selectable options, and only (4) was the correct answer. It did not specify the name of the C compiler, hardware, or the OS.

2009年6月11日 · A shift, whether it alters the value or not (and a shift by zero bits does not alter it), is usually a single CPU cycle on most CPUs. The ternary operation has a comparison and at least one (if not two) jumps, additionally to a possible shift.

2012年11月8日 · Very good explanation, but I am facing a problem while doing bit-wise left shift. The compiler seems to take the bits in group of 32 but I need to work only on 8 bits while doing the cyclic left shift.