x / 2更清晰，x >> 1快不了多少(根据一个微基准测试，对于Java JVM快30%左右)。正如其他人所注意到的，对于负数，舍入略有不同，所以当您想处理负数时必须考虑这一点。一些编译器可能会自动将x / 2转换为x >> 1，如果他们知道这个数字不可能是负数(即使我无法验证这一点)。

即使x / 2可能不使用(慢)除法CPU指令，因为一些捷径是可能的，但它仍然比x >> 1慢。

(This is a C / C++ question, other programming languages have more operators. For Java there is also the unsigned right shift, x >>> 1, which is again different. It allows to correctly calculate the mean (average) value of two values, so that (a + b) >>> 1 will return the mean value even for very large values of a and b. This is required for example for binary search if the array indices can get very large. There was a bug in many versions of binary search, because they used (a + b) / 2 to calculate the average. This doesn't work correctly. The correct solution is to use (a + b) >>> 1 instead.)

显然，如果你是在为下一个阅读你的代码的人写代码，那么你应该追求“x/2”的清晰度。

然而，如果速度是你的目标，那就两种方法都试一试，把握好时间。几个月前，我做了一个位图卷积例程，它涉及到在一个整数数组中步进，并将每个元素除以2。我做了各种各样的事情来优化它，包括用“x>>1”代替“x/2”的老技巧。

当我计算这两种方式时，我惊奇地发现x/2比x>>1快

这是使用Microsoft VS2008 c++并打开默认优化。

我们有很多理由支持使用x = x / 2;以下是一些例子:

it expresses your intent more clearly (assuming you're not dealing with bit twiddling register bits or something) the compiler will reduce this to a shift operation anyway even if the compiler didn't reduce it and chose a slower operation than the shift, the likelihood that this ends up affecting your program's performance in a measurable way is itself vanishingly small (and if it does affect it measurably, then you have an actual reason to use a shift) if the division is going to be part of a larger expression, you're more likely to get the precedence right if you use the division operator: x = x / 2 + 5; x = x >> 1 + 5; // not the same as above signed arithmetic might complicate things even more than the precedence problem mentioned above to reiterate - the compiler will already do this for you anyway. In fact, it'll convert division by a constant to a series of shifts, adds, and multiplies for all sorts of numbers, not just powers of two. See this question for links to even more information about this.

简而言之，当你真正想要进行乘法或除法运算时，编写移位代码并没有什么好处，除了可能会增加引入错误的可能性。自从编译器不够聪明到在适当的时候优化这类事情到移位以来，已经过去了。

Knuth说:

过早的优化是万恶之源。

所以我建议用x /= 2;

这样代码很容易理解，而且我认为这种形式的操作优化，对处理器来说不会有太大的区别。

在性能方面。CPU的移位运算比除法运算快得多。 所以除以2或乘以2等都可以从移位运算中获益。

至于外观和感觉。作为工程师，我们什么时候变得如此依赖化妆品，连漂亮的女士都不用!：）

第一个看起来像除法吗?不。如果你想除法，用x / 2。如果可能的话，编译器可以优化它使用位移位(它被称为强度减少)，这使得它成为一个无用的微优化，如果你自己做它。