This is Windows 7 32-bit, Visual Studio 2017, in a C file.
int i = 65536;
As expected,
i >> 0 = 65536
i >> 1 = 32768
:
:
i >> 16 = 1
i >> 17 to 31 = 0.
i >> 32 is magically 65536 again though. How is that legal?
ISO/IEC 9899:TC2 says the following and I assume C++ specs are the same?
The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type or if E1 has a signed type and a nonnegative value, the value of the result is the integral part of the quotient of E1 / 2^E2. If E1 has a signed type and a negative value, the resulting value is implementation-defined.
... If the value of the right operand is negative or is greater than or equal to the width of the promoted left operand , the behavior is undefined .
With clang, gcc, and icc, you'll get a warning if you attempt to shift by a constant that's greater or equal to the width of the shifted value, and you don't even need any extra command-line flags.
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