Python 运算符

什么是运算符？

本章节主要说明Python的运算符。举个简单的例子 4 +5 = 9 。 例子中，4和5被称为操作数，"+"号为运算符。

Python语言支持以下类型的运算符:

• 算术运算符
• 比较（关系）运算符
• 赋值运算符
• 逻辑运算符
• 位运算符
• 成员运算符
• 身份运算符
• 运算符优先级

接下来让我们一个个来学习Python的运算符。

Python算术运算符

以下假设变量a为10，变量b为20：

以下实例演示了Python所有算术运算符的操作：

 #!/usr/bin/python  a = 21 b = 10 c = 0  c = a + b print "Line 1 - Value of c is ", c  c = a - b print "Line 2 - Value of c is ", c   c = a * b print "Line 3 - Value of c is ", c   c = a / b print "Line 4 - Value of c is ", c   c = a % b print "Line 5 - Value of c is ", c  a = 2 b = 3 c = a**b  print "Line 6 - Value of c is ", c  a = 10 b = 5 c = a//b  print "Line 7 - Value of c is ", c 

尝试一下 »

以上实例输出结果：

 Line 1 - Value of c is 31 Line 2 - Value of c is 11 Line 3 - Value of c is 210 Line 4 - Value of c is 2 Line 5 - Value of c is 1 Line 6 - Value of c is 8 Line 7 - Value of c is 2 

Python比较运算符

以下假设变量a为10，变量b为20：

以下实例演示了Python所有比较运算符的操作：

 #!/usr/bin/python  a = 21 b = 10 c = 0  if ( a == b ):    print "Line 1 - a is equal to b" else:    print "Line 1 - a is not equal to b"  if ( a != b ):    print "Line 2 - a is not equal to b" else:    print "Line 2 - a is equal to b"  if ( a <> b ):    print "Line 3 - a is not equal to b" else:    print "Line 3 - a is equal to b"  if ( a < b ):    print "Line 4 - a is less than b"  else:    print "Line 4 - a is not less than b"  if ( a > b ):    print "Line 5 - a is greater than b" else:    print "Line 5 - a is not greater than b"  a = 5; b = 20; if ( a <= b ):    print "Line 6 - a is either less than or equal to  b" else:    print "Line 6 - a is neither less than nor equal to  b"  if ( b >= a ):    print "Line 7 - b is either greater than  or equal to b" else:    print "Line 7 - b is neither greater than  nor equal to b" 

以上实例输出结果：

 Line 1 - a is not equal to b Line 2 - a is not equal to b Line 3 - a is not equal to b Line 4 - a is not less than b Line 5 - a is greater than b Line 6 - a is either less than or equal to b Line 7 - b is either greater than or equal to b  

Python赋值运算符

以下假设变量a为10，变量b为20：

以下实例演示了Python所有赋值运算符的操作：

 #!/usr/bin/python  a = 21 b = 10 c = 0  c = a + b print "Line 1 - Value of c is ", c  c += a print "Line 2 - Value of c is ", c   c *= a print "Line 3 - Value of c is ", c   c /= a  print "Line 4 - Value of c is ", c   c  = 2 c %= a print "Line 5 - Value of c is ", c  c **= a print "Line 6 - Value of c is ", c  c //= a print "Line 7 - Value of c is ", c 

以上实例输出结果：

 Line 1 - Value of c is 31 Line 2 - Value of c is 52 Line 3 - Value of c is 1092 Line 4 - Value of c is 52 Line 5 - Value of c is 2 Line 6 - Value of c is 2097152 Line 7 - Value of c is 99864 

Python位运算符

按位运算符是把数字看作二进制来进行计算的。Python中的按位运算法则如下：

以下实例演示了Python所有位运算符的操作：

 #!/usr/bin/python  a = 60            # 60 = 0011 1100  b = 13            # 13 = 0000 1101  c = 0  c = a & b;        # 12 = 0000 1100 print "Line 1 - Value of c is ", c  c = a | b;        # 61 = 0011 1101  print "Line 2 - Value of c is ", c  c = a ^ b;        # 49 = 0011 0001 print "Line 3 - Value of c is ", c  c = ~a;           # -61 = 1100 0011 print "Line 4 - Value of c is ", c  c = a << 2;       # 240 = 1111 0000 print "Line 5 - Value of c is ", c  c = a >> 2;       # 15 = 0000 1111 print "Line 6 - Value of c is ", c 

以上实例输出结果：

 Line 1 - Value of c is 12 Line 2 - Value of c is 61 Line 3 - Value of c is 49 Line 4 - Value of c is -61 Line 5 - Value of c is 240 Line 6 - Value of c is 15 

Python逻辑运算符

Python语言支持逻辑运算符，以下假设变量a为10，变量b为20：

以下实例演示了Python所有逻辑运算符的操作：

 #!/usr/bin/python  a = 10 b = 20 c = 0  if ( a and b ):    print "Line 1 - a and b are true" else:    print "Line 1 - Either a is not true or b is not true"  if ( a or b ):    print "Line 2 - Either a is true or b is true or both are true" else:    print "Line 2 - Neither a is true nor b is true"   a = 0 if ( a and b ):    print "Line 3 - a and b are true" else:    print "Line 3 - Either a is not true or b is not true"  if ( a or b ):    print "Line 4 - Either a is true or b is true or both are true" else:    print "Line 4 - Neither a is true nor b is true"  if not( a and b ):    print "Line 5 - Either a is not true or b is  not true or both are not true" else:    print "Line 5 - a and b are true" 

以上实例输出结果：

 Line 1 - a and b are true Line 2 - Either a is true or b is true or both are true Line 3 - Either a is not true or b is not true Line 4 - Either a is true or b is true or both are true Line 5 - Either a is not true or b is  not true or both are not true 

Python成员运算符

除了以上的一些运算符之外，Python还支持成员运算符，测试实例中包含了一系列的成员，包括字符串，列表或元组。

以下实例演示了Python所有成员运算符的操作：

 #!/usr/bin/python  a = 10 b = 20 list = [1, 2, 3, 4, 5 ];  if ( a in list ):    print "Line 1 - a is available in the given list" else:    print "Line 1 - a is not available in the given list"  if ( b not in list ):    print "Line 2 - b is not available in the given list" else:    print "Line 2 - b is available in the given list"  a = 2 if ( a in list ):    print "Line 3 - a is available in the given list" else:    print "Line 3 - a is not available in the given list" 

以上实例输出结果：

 Line 1 - a is not available in the given list Line 2 - b is not available in the given list Line 3 - a is available in the given list 

Python身份运算符

身份运算符用于比较两个对象的存储单元

以下实例演示了Python所有身份运算符的操作：

 #!/usr/bin/python  a = 20 b = 20  if ( a is b ):    print "Line 1 - a and b have same identity" else:    print "Line 1 - a and b do not have same identity"  if ( id(a) == id(b) ):    print "Line 2 - a and b have same identity" else:    print "Line 2 - a and b do not have same identity"  b = 30 if ( a is b ):    print "Line 3 - a and b have same identity" else:    print "Line 3 - a and b do not have same identity"  if ( a is not b ):    print "Line 4 - a and b do not have same identity" else:    print "Line 4 - a and b have same identity" 

以上实例输出结果：

 Line 1 - a and b have same identity Line 2 - a and b have same identity Line 3 - a and b do not have same identity Line 4 - a and b do not have same identity  

Python运算符优先级

以下表格列出了从最高到最低优先级的所有运算符：

以下实例演示了Python所有运算符优先级的操作：

 #!/usr/bin/python  a = 20 b = 10 c = 15 d = 5 e = 0  e = (a + b) * c / d       #( 30 * 15 ) / 5 print "Value of (a + b) * c / d is ",  e  e = ((a + b) * c) / d     # (30 * 15 ) / 5 print "Value of ((a + b) * c) / d is ",  e  e = (a + b) * (c / d);    # (30) * (15/5) print "Value of (a + b) * (c / d) is ",  e  e = a + (b * c) / d;      #  20 + (150/5) print "Value of a + (b * c) / d is ",  e 

以上实例输出结果：

 Value of (a + b) * c / d is 90 Value of ((a + b) * c) / d is 90 Value of (a + b) * (c / d) is 90 Value of a + (b * c) / d is 50