在C或C ++中>> =的含义是什么？ [英] What is the meaning of >>= in C or C++?

问题描述

C或C ++中>> = 符号的含义是什么？它有什么特别的名字吗？

我有一个CUDA代码中的 for 循环，看起来像这样

  for（int offset = blockDim.x; offset> 0; offset>> = 1）
 {
 //一些代码
} 
  

如何使用 >> = / code>符号是右移的赋值形式，即 x>> = y; 是 x>> y; （除非重载意味着不同的东西）。

右移1相当于除以2.该代码看起来像个人不信任编译器做最基本的优化，应该等效于：

  for（int offset = blockDim.x ; offset> 0; offset / = 2）{...} 
  

这里：

http://en.wikipedia.org/wiki / Binary_shift＃Bit_shifts

What is the meaning of the >>= symbol in C or C++? Does it have any particular name?

I have this for loop in some CUDA code which looks like this

for(int offset=blockDim.x; offset>0; offset >>=1)
{
   //Some code 
}

How does the offset variable get modfied with the >>= operator?

解决方案

The >>= symbol is the assignment form of right-shift, that is x >>= y; is short for x = x >> y; (unless overloaded to mean something different).

Right shifting by 1 is equivalent to divide by 2. That code looks like someone doesn't trust the compiler to do the most basic optimizations, and should be equivalent to:

for( int offset = blockDim.x; offset > 0; offset /= 2 ){ ... }

More information about bitwise operations here:

http://en.wikipedia.org/wiki/Binary_shift#Bit_shifts

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