📅 最后修改于: 2020-10-24 08:52:59 🧑 作者: Mango
可以将运算符定义为负责两个操作数之间特定操作的符号。运算符是程序的基础，使用特定的编程语言在其上构建逻辑。 Python提供了各种运算符，其描述如下。
算术运算运算符用于在两个操作数之间执行算术运算。它包括+(加法)，-(减法)，*(乘法)，/(除法)，％(提醒)，//(底数除法)和指数(**)运算符。
请考虑下表，以详细了解算术运算运算符。
| Operator | Description |
|---|---|
| + (Addition) | It is used to add two operands. For example, if a = 20, b = 10 => a+b = 30 |
| – (Subtraction) | It is used to subtract the second operand from the first operand. If the first operand is less than the second operand, the value results negative. For example, if a = 20, b = 10 => a – b = 10 |
| / (divide) | It returns the quotient after dividing the first operand by the second operand. For example, if a = 20, b = 10 => a/b = 2.0 |
| * (Multiplication) | It is used to multiply one operand with the other. For example, if a = 20, b = 10 => a * b = 200 |
| % (reminder) | It returns the reminder after dividing the first operand by the second operand. For example, if a = 20, b = 10 => a%b = 0 |
| ** (Exponent) | It is an exponent operator represented as it calculates the first operand power to the second operand. |
| // (Floor division) | It gives the floor value of the quotient produced by dividing the two operands. |
运算符用于比较两个操作数的值，并相应地返回布尔值true或false。运算符在下表中进行了描述。
| Operator | Description |
|---|---|
| == | If the value of two operands is equal, then the condition becomes true. |
| != | If the value of two operands is not equal, then the condition becomes true. |
| <= | If the first operand is less than or equal to the second operand, then the condition becomes true. |
| >= | If the first operand is greater than or equal to the second operand, then the condition becomes true. |
| > | If the first operand is greater than the second operand, then the condition becomes true. |
| < | If the first operand is less than the second operand, then the condition becomes true. |
赋值运算符用于将右表达式的值赋给左操作数。下表描述了赋值运算符。
| Operator | Description |
|---|---|
| = | It assigns the value of the right expression to the left operand. |
| += | It increases the value of the left operand by the value of the right operand and assigns the modified value back to left operand. For example, if a = 10, b = 20 => a+ = b will be equal to a = a+ b and therefore, a = 30. |
| -= | It decreases the value of the left operand by the value of the right operand and assigns the modified value back to left operand. For example, if a = 20, b = 10 => a- = b will be equal to a = a- b and therefore, a = 10. |
| *= | It multiplies the value of the left operand by the value of the right operand and assigns the modified value back to then the left operand. For example, if a = 10, b = 20 => a* = b will be equal to a = a* b and therefore, a = 200. |
| %= | It divides the value of the left operand by the value of the right operand and assigns the reminder back to the left operand. For example, if a = 20, b = 10 => a % = b will be equal to a = a % b and therefore, a = 0. |
| **= | a**=b will be equal to a=a**b, for example, if a = 4, b =2, a**=b will assign 4**2 = 16 to a. |
| //= | A//=b will be equal to a = a// b, for example, if a = 4, b = 3, a//=b will assign 4//3 = 1 to a. |
按位运算运算符对两个操作数的值进行逐位运算。考虑以下示例。
例如，
if a = 7
b = 6
then, binary (a) = 0111
binary (b) = 0011
hence, a & b = 0011
a | b = 0111
a ^ b = 0100
~ a = 1000
| Operator | Description |
|---|---|
| & (binary and) | If both the bits at the same place in two operands are 1, then 1 is copied to the result. Otherwise, 0 is copied. |
| | (binary or) | The resulting bit will be 0 if both the bits are zero; otherwise, the resulting bit will be 1. |
| ^ (binary xor) | The resulting bit will be 1 if both the bits are different; otherwise, the resulting bit will be 0. |
| ~ (negation) | It calculates the negation of each bit of the operand, i.e., if the bit is 0, the resulting bit will be 1 and vice versa. |
| << (left shift) | The left operand value is moved left by the number of bits present in the right operand. |
| >> (right shift) | The left operand is moved right by the number of bits present in the right operand. |
逻辑运算符主要用于表达式评估中以做出决策。 Python支持以下逻辑运算符。
| Operator | Description |
|---|---|
| and | If both the expression are true, then the condition will be true. If a and b are the two expressions, a → true, b → true => a and b → true. |
| or | If one of the expressions is true, then the condition will be true. If a and b are the two expressions, a → true, b → false => a or b → true. |
| not | If an expression a is true, then not (a) will be false and vice versa. |
Python成员运算符用于检查Python数据结构中值的成员资格。如果该值存在于数据结构中，则结果值为true，否则返回false。
| Operator | Description |
|---|---|
| in | It is evaluated to be true if the first operand is found in the second operand (list, tuple, or dictionary). |
| not in | It is evaluated to be true if the first operand is not found in the second operand (list, tuple, or dictionary). |
身份运算符用于确定元素是特定的类还是类型。
| Operator | Description |
|---|---|
| is | It is evaluated to be true if the reference present at both sides point to the same object. |
| is not | It is evaluated to be true if the reference present at both sides do not point to the same object. |
找出运算符的优先级至关重要，因为它使我们知道应该首先评估哪个运算符。下面给出了Python运算符的优先级表。
| Operator | Description |
|---|---|
| ** | The exponent operator is given priority over all the others used in the expression. |
| ~ + – | The negation, unary plus, and minus. |
| * / % // | The multiplication, divide, modules, reminder, and floor division. |
| + – | Binary plus, and minus |
| >> << | Left shift. and right shift |
| & | Binary and. |
| ^ | | Binary xor, and or |
| <= < > >= | Comparison operators (less than, less than equal to, greater than, greater then equal to). |
| <> == != | Equality operators. |
| = %= /= //= -= += *= **= |
Assignment operators |
| is is not | Identity operators |
| in not in | Membership operators |
| not or and | Logical operators |