VB.Net - 运算符

2020-11-06 16:40 更新

运算符是一个符号，通知编译器执行特定的数学或逻辑操作。 VB.Net丰富的内置运算符，并提供以下类型的常用运算符：

算术运算符
比较运算符
逻辑/位运算符
位移位运算符
赋值运算符
其他运算符

本教程将介绍最常用的运算符。

算术运算符

下表显示了VB.Net支持的所有算术运算符。假设变量A保持2，变量B保持7，则：

运算符	描述	例
^	Raises one operand to the power of anothe 将一个操作数作为为另一个的幂	B^A will give 49
+	Adds two operand 添加两个操作数s	A + B will give 9
-	Subtracts second operand from the first 从第一个操作数中减去第二个操作数	A - B will give -5
*	Multiplies both operands 将两个操作数相乘	A * B will give 14
/	Divides one operand by another and returns a floating point result 将一个操作数除以另一个操作数，并返回一个浮点结果	B / A will give 3.5
\	Divides one operand by another and returns an integer result 将一个操作数除以另一个操作数，并返回一个整数结果	B \ A will give 3
MOD	Modulus Operator and remainder of after an integer division 模数运算符和整数除法后的余数	B MOD A will give 1

比较运算符

下表显示了VB.Net支持的所有比较运算符。假设变量A保持10，变量B保持20，则：

显示示例

运算符	描述	例
=	Checks if the values of two operands are equal or not; if yes, then condition becomes true. 检查两个操作数的值是否相等; 如果是，则条件变为真。	（A = B）是不正确的。
<>	Checks if the values of two operands are equal or not; if values are not equal, then condition becomes true. 检查两个操作数的值是否相等; 如果值不相等，则条件为真。	（A<>B）为真。
>	Checks if the value of left operand is greater than the value of right operand; if yes, then condition becomes true. 检查左操作数的值是否大于右操作数的值; 如果是，则条件变为真。	（A> B）是不正确的。
<	Checks if the value of left operand is less than the value of right operand; if yes, then condition becomes true. 检查左操作数的值是否小于右操作数的值; 如果是，则条件变为真。	（A <B）为真。
> =	Checks if the value of left operand is greater than or equal to the value of right operand; if yes, then condition becomes true. 检查左操作数的值是否大于或等于右操作数的值; 如果是，则条件变为真。	（A> = B）是不正确的。
<=	Checks if the value of left operand is less than or equal to the value of right operand; if yes, then condition becomes true. 检查左操作数的值是否小于或等于右操作数的值; 如果是，则条件变为真。	（A <= B）为真。

除了上述情况外，VB.Net提供了三个比较运算符，我们将在以后的章节中使用; 然而，我们在这里给出一个简短的描述。

1、Is运算符 - 它比较两个对象引用变量，并确定两个对象引用是否引用相同的对象，而不执行值比较。如果object1和object2都引用完全相同的对象实例，则result为True; 否则，result为False。

2、IsNot运算符 - 它还比较两个对象引用变量，并确定两个对象引用是否引用不同的对象。如果object1和object2都引用完全相同的对象实例，则result为False; 否则，result为True。

3、Like运算符 - 它将字符串与模式进行比较。

逻辑/位运算符

下表显示了VB.Net支持的所有逻辑运算符。假设变量A保持布尔值True，变量B保持布尔值False，则：

显示示例

运算符	描述	例
And	It is the logical as well as bitwise AND operator. If both the operands are true, then condition becomes true. This operator does not perform short-circuiting, i.e., it evaluates both the expressions. 它是逻辑以及按位AND运算符。如果两个操作数都为真，则条件为真。此运算符不执行短路，即，它评估两个表达式。	（A和B）为假。
Or	It is the logical as well as bitwise OR operator. If any of the two operands is true, then condition becomes true. This operator does not perform short-circuiting, i.e., it evaluates both the expressions. 它是逻辑以及按位或运算符。如果两个操作数中的任何一个为真，则条件为真。此运算符不执行短路，即，它评估两个表达式。	（A或B）为真。
Not	It is the logical as well as bitwise NOT operator. Use to reverses the logical state of its operand. If a condition is true, then Logical NOT operator will make false. 它是逻辑以及按位非运算符。用于反转其操作数的逻辑状态。如果条件为真，则逻辑非运算符将为假。	没有（A和B）为真。
Xor	It is the logical as well as bitwise Logical Exclusive OR operator. It returns True if both expressions are True or both expressions are False; otherwise it returns False. This operator does not perform short-circuiting, it always evaluates both expressions and there is no short-circuiting counterpart of this operator. 它是逻辑以及按位逻辑异或运算符。如果两个表达式都为True或两个表达式都为False，则返回True; 否则返回False。该运算符不会执行短路，它总是评估这两个表达式，并且没有该运算符的短路对应。	异或B为真。
AndAlso	It is the logical AND operator. It works only on Boolean data. It performs short-circuiting. 它是逻辑 AND 运算符。它仅适用于布尔型数据。它执行短路。	（A AndAlso运算B）为假。
OrElse	It is the logical OR operator. It works only on Boolean data. It performs short-circuiting. 它是逻辑或运算符。它只适用于布尔数据。它执行短路。	（A OrElse运算B）为真。
IsFalse	It determines whether an expression is False. 它确定表达式是否为假。
IsTrue	It determines whether an expression is True. 它确定表达式是否为真。

位移运算符

我们已经讨论了按位运算符。位移运算符对二进制值执行移位操作。在进入位移运算符之前，让我们来了解位操作。

按位运算符处理位并执行逐位操作。＆，|和^的真值表如下：

p	q	p＆Q	p \| q	p ^ Q
0	0	0	0	0
0	1	0	1	1
1	1	1	1	0
1	0	0	1	1

假设A = 60; 和B = 13; 现在的二进制格式，他们将如下：

A = 0011 1100

B = 0000 1101

-----------------

A＆B = 0000 1100

A | B = 0011 1101

A ^ B = 0011 0001

〜A = 1100 0011

我们已经看到VB.Net支持的Bitwise运算符是And，Or，Xor和Not。位移位算子分别是用于左移和右移的>>和<<。

假设变量A保持60，变量B保持13，则：

显示示例

运算符描述示例
And Bitwise AND Operator copies a bit to the result if it exists in both operands.
如果两个操作数都存在，则按位AND运算符将一个位复制到结果。 (A AND B) will give 12, which is 0000 1100
Or Binary OR Operator copies a bit if it exists in either operand.
二进制OR运算符复制一个位，如果它存在于任一操作数。 (A Or B) will give 61, which is 0011 1101
Xor Binary XOR Operator copies the bit if it is set in one operand but not both.
二进制XOR运算符复制该位，如果它在一个操作数中设置，但不是两个操作数。 (A Xor B) will give 49, which is 0011 0001
Not Binary Ones Complement Operator is unary and has the effect of 'flipping' bits.
二进制补码运算符是一元的，具有“翻转”位的效果。 (Not A ) will give -61, which is 1100 0011 in 2's complement form due to a signed binary number.
<< Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.
二进制左移位运算符。左操作数值向左移动由右操作数指定的位数。 A << 2 will give 240, which is 1111 0000
>> Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.
二进制右移运算符。左操作数值向右移动由右操作数指定的位数。 A >> 2 will give 15, which is 0000 1111

运算符	描述	示例
And	Bitwise AND Operator copies a bit to the result if it exists in both operands. 如果两个操作数都存在，则按位AND运算符将一个位复制到结果。	(A AND B) will give 12, which is 0000 1100
Or	Binary OR Operator copies a bit if it exists in either operand. 二进制OR运算符复制一个位，如果它存在于任一操作数。	(A Or B) will give 61, which is 0011 1101
Xor	Binary XOR Operator copies the bit if it is set in one operand but not both. 二进制XOR运算符复制该位，如果它在一个操作数中设置，但不是两个操作数。	(A Xor B) will give 49, which is 0011 0001
Not	Binary Ones Complement Operator is unary and has the effect of 'flipping' bits. 二进制补码运算符是一元的，具有“翻转”位的效果。	(Not A ) will give -61, which is 1100 0011 in 2's complement form due to a signed binary number.
<<	Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. 二进制左移位运算符。左操作数值向左移动由右操作数指定的位数。	A << 2 will give 240, which is 1111 0000
>>	Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. 二进制右移运算符。左操作数值向右移动由右操作数指定的位数。	A >> 2 will give 15, which is 0000 1111

赋值运算符

VB.Net支持以下赋值运算符：

显示示例

运算符	描述	例
=	Simple assignment operator, Assigns values from right side operands to left side operand 简单赋值操作符，将值从右侧操作数分配给左侧操作数	C = A + B A + B将赋值为C
+ =	Add AND assignment operator, It adds right operand to the left operand and assigns the result to left operand 添加AND赋值运算符，向左操作数添加右操作数，并将结果赋值给左操作数	C + = A等于C = C + A
- =	Subtract AND assignment operator, It subtracts right operand from the left operand and assigns the result to left operand 减法AND赋值运算符，它从左操作数中减去右操作数，并将结果赋值给左操作数	Ç - = A等于C = C - 一个
* =	Multiply AND assignment operator, It multiplies right operand with the left operand and assigns the result to left operand 乘法AND赋值运算符，它将右操作数与左操作数相乘，并将结果赋值给左操作数	C * = A等于C = C * A
/ =	Divide AND assignment operator, It divides left operand with the right operand and assigns the result to left operand (floating point division) 除法AND赋值运算符，它用右操作数划分左操作数，并将结果分配给左操作数（浮点除法）	C / = A等于C = C / A
\ =	Divide AND assignment operator, It divides left operand with the right operand and assigns the result to left operand (Integer division) 除法AND赋值运算符，它用右操作数划分左操作数，并将结果分配给左操作数（整数除法）	ç = A等于C = C A
^ =	Exponentiation and assignment operator. It raises the left operand to the power of the right operand and assigns the result to left operand. 指数和赋值运算符。它将左操作数提升为右操作数的幂，并将结果分配给左操作数。	C ^ = A等于C = C ^ A
<< =	Left shift AND assignment operator 左移AND赋值运算符	C语言的<< = 2是同C = C << 2
>> =	Right shift AND assignment operator 右移AND赋值运算符	C >> = 2 >> 2同C = C
＆=	Concatenates a String expression to a String variable or property and assigns the result to the variable or property. 将String表达式连接到String变量或属性，并将结果分配给变量或属性。	STR1＆= STR2赛车是一样的 STR1 = STR1与STR2

其他运算符

有很少其他重要的操作系统支持VB.Net。

显示示例

运算符	描述	例
AddressOf	Returns the address of a procedure. 返回过程的地址。	AddHandler Button1.Click, AddressOf Button1_Click
Await	It is applied to an operand in an asynchronous method or lambda expression to suspend execution of the method until the awaited task completes. 它应用于异步方法或lambda表达式中的操作数，以暂停该方法的执行，直到等待的任务完成。	Dim result As res = Await AsyncMethodThatReturnsResult() Await AsyncMethod()
GetType	It returns a Type object for the specified type. The Type object provides information about the type such as its properties, methods, and events. 它返回指定类型的Type对象。 Type对象提供有关类型的信息，例如其属性，方法和事件。	MsgBox(GetType(Integer).ToString())
Function Expression	It declares the parameters and code that define a function lambda expression. 它声明定义函数lambda表达式的参数和代码。	Dim add5 = Function(num As Integer) num + 5 'prints 10 Console.WriteLine(add5(5))
If	It uses short-circuit evaluation to conditionally return one of two values. The If operator can be called with three arguments or with two arguments. 它使用短路评估有条件地返回两个值之一。可以使用三个参数或两个参数调用If运算符。	Dim num = 5 Console.WriteLine(If(num >= 0, "Positive", "Negative"))

VB.Net中的运算符优先级

运算符优先级确定表达式中的术语分组。这会影响表达式的计算方式。某些运算符比其他运算符具有更高的优先级; 例如，乘法运算符的优先级高于加法运算符：

例如，x = 7 + 3 * 2; 这里，x被分配13，而不是20，因为operator *具有比+高的优先级，所以它首先乘以3 * 2，然后加到7。

这里，具有最高优先级的运算符出现在表的顶部，具有最低优先级的运算符出现在底部。在表达式中，将首先计算较高优先级运算符。

显示示例

运算符	优先级
Await	最高
Exponentiation (^)
Unary identity and negation (+, -)
Multiplication and floating-point division (*, /)
Integer division (\)
Modulus arithmetic (Mod)
Addition and subtraction (+, -)
Arithmetic bit shift (<<, >>)
All comparison operators (=, <>, <, <=, >, >=, Is, IsNot, Like, TypeOf...Is)
Negation (Not)
Conjunction (And, AndAlso)
Inclusive disjunction (Or, OrElse)
Exclusive disjunction (Xor)	最低