“>>>"是什么意思在java中是什么意思? [英] what does ">>>" mean in java?
问题描述
我发现此代码可以在 SO 在这里发帖.但我不明白这一行是什么意思 int mid = (low + high) >>>1;
I found this code to find duplicates in SO post here.
but I dont understand what this line means int mid = (low + high) >>> 1;
private static int findDuplicate(int[] array) {
int low = 0;
int high = array.length - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
System.out.println(mid);
int midVal = array[mid];
if (midVal == mid)
low = mid + 1;
else
high = mid - 1;
}
return high;
}
推荐答案
>>> 操作符是 Java 中的无符号右移运算符.它有效地将操作数除以 2 到右操作数的幂，或者这里只是 2.
The >>> operator is the unsigned right bit-shift operator in Java. It effectively divides the operand by 2 to the power of the right operand, or just 2 here.
>> 和 >>> 之间的区别只会在移动负数时出现.>>> 运算符将 1 位移入最高有效位，如果它是 1，并且 >>>;> 无论如何都会在 0 中移动.
The difference between >> and >>> would only show up when shifting negative numbers. The >> operator shifts a 1 bit into the most significant bit if it was a 1, and the >>> shifts in a 0 regardless.
更新:
让我们平均 1 和 2147483647 (Integer.MAX_VALUE).我们可以轻松地进行数学计算:
Let's average 1 and 2147483647 (Integer.MAX_VALUE). We can do the math easily:
(1 + 2147483647) / 2 = 2147483648 / 2 = 1073741824
现在，使用代码 (low + high)/2，这些是涉及的位:
Now, with the code (low + high) / 2, these are the bits involved:
1: 00000000 00000000 00000000 00000001
+2147483647: 01111111 11111111 11111111 11111111
================================================
-2147483648: 10000000 00000000 00000000 00000000 // Overflow
/2
================================================
-1073741824: 11000000 00000000 00000000 00000000 // Signed divide, same as >> 1.
让我们转移"到>>>:
1: 00000000 00000000 00000000 00000001
+2147483647: 01111111 11111111 11111111 11111111
================================================
-2147483648: 10000000 00000000 00000000 00000000 // Overflow
>>> 1
================================================
+1073741824: 01000000 00000000 00000000 00000000 // Unsigned shift right.
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