按住Shift键在java中操作实现 [英] Shift operation implementation in java

问题描述

我最近使用Java中的移位运算符，并注意到＆GT;＆GT; 运营商不具备的含义＆GT相同;＆GT; C语言在Java ＆GT;＆GT; 签订的转变，保持第一位在同一价值。在Java中等于C的转变是在＆GT;＆GT;＆GT; 运营商。左移操作符（＆LT;＆LT; ）是C相同，只是转移忽略的第一位。

I recently used the shift operators in Java and noticed that the >> operator does not have the same meaning as >> in C. In Java >> is Signed shift that keeps the first bit at the same value. In Java the equivalent to C shift is the >>> operator. The left shift operator (<<) is the same as in C and just shifts ignoring the first bit.

我不知道的东西。

• 为什么会做出这种改变？


• 为什么不标记一致的，因此>>和＆lt;＆LT;签署移和>>>和＆lt;＆LT;＆LT;是无符号？


• 是否有一个签名移位运算符有什么用处？

推荐答案

有从未任何需要的标志感知左移，由于2：补重新presentation存储在最显著位的符号

There is never any need for a sign-aware left shift, since 2:s complement representation stores the sign in the most significant bit.

有一个值之间没有区别移1位左某种符号感知的方式，有什么可以做不同的。位左移，将在最显著位0，就大功告成了。

There's no difference between a value shifted one bit to the left in some kind of "sign-aware" manner, there's nothing you can do differently. Shift the bits to the left, insert a 0 in the least significant bit, and you're done.

通过符号数，右移是的不的那么清楚，这就是为什么有两家运营商。

With signed numbers, shifting right is not so clear-cut, which is why there are two operators.

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