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2017年9月10日 (日) 07:56 Allblue

2017-09-10T07:56:41Z

2017年9月10日 (日) 07:56 Allblue

2017-09-10T07:56:15Z

Admin：以“The bitwise NOT operator in C++ is the tilde character ~. Unlike & and |, the bitwise NOT operator is applied to a single operand to its right. Bitwise NOT changes e...”为内容创建页面

2015-08-19T09:36:09Z

以“The bitwise NOT operator in C++ is the tilde character ~. Unlike & and |, the bitwise NOT operator is applied to a single operand to its right. Bitwise NOT changes e...”为内容创建页面

新页面

The bitwise NOT operator in C++ is the tilde character ~. Unlike & and |, the bitwise NOT operator is applied to a single operand to its right. Bitwise NOT changes each bit to its opposite: 0 becomes 1, and 1 becomes 0. For example:

0 1 operand1
----------
1 0 ~ operand1
int a = 103; // binary: 0000000001100111
int b = ~a; // binary: 1111111110011000 = -104

You might be surprised to see a negative number like -104 as the result of this operation. This is because the highest bit in an int variable is the so-called sign bit. If the highest bit is 1, the number is interpreted as negative. This encoding of positive and negative numbers is referred to as two's complement. For more information, see the Wikipedia article on two's complement.

As an aside, it is interesting to note that for any integer x, ~x is the same as -x-1.

At times, the sign bit in a signed integer expression can cause some unwanted surprises.

----

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@@ 第1行： / 第1行： @@
  在C++中，按位取反用符号"~"表示。不像按位与(&)和按位或(|),按位取反(^)用于单个操作数，用来改变操作数上每一位的值，将0变为1，或将1变为0。比如：<br>
-<pre style="color:green">
+<pre style="color:dimgray">
   1       运算数1
     ------
@@ 第9行： / 第9行： @@
 位的用法相同。如下：<br>
-<pre style="color:green">
+<pre style="color:dimgray">
      int a = 103;    // 二进制:  0000000001100111
      int b = ~a;     // 二进制:  1111111110011000 = -104

@@ 第1行： / 第1行： @@
-  1    operand1
+在C++中，按位取反用符号"~"表示。不像按位与(&)和按位或(|),按位取反(^)用于单个操作数，用来改变操作数上每一位的值，将0变为1，或将1变为0。比如：<br>
-    ----------
+<pre style="color:green">
-  0   ~ operand1
+  1       运算数1
-    int a = 103;    // binary:  0000000001100111
+    ------
-    int b = ~a;     // binary:  1111111110011000 = -104
+  0       运算数1取反
-As an aside, it is interesting to note that for any integer x, ~x is the same as -x-1.
+位的用法相同。如下：<br>