c++ - Setting all bits in int64_t

Question

From following code I expect to set all bits in x to 1, but somehow only first 32 bits are set:

int64_t x = 0xFFFFFFFF;
x<<32;
x|=0xFFFFFFFF;

Note: printing x after each line results in 4294967295 (32 lower bits set to 1). Also, tried using numeric_limits<int64_t>::min() with no success. My question is how to set all bits in x? Using RHEL5.5.

Thx

Answer 1

x<<32计算x左移 32 位的结果，对 value 不做任何事情。你想x <<= 32改用。

Answer 2

为什么不int64_t x = -1呢？还是uint64_t x = ~0？

Answer 3

这将起作用：

int64_t x = ~0LL;   (iner

或者

int64_t x = -1LL;

您可能会逃脱没有LL，但不能保证 - 取决于编译器。