比较(关系)运算符比较它们两边的值，并确定它们之间的关系。它们也称为关系运算符。假设变量a的值10，变量b的值是21，则 -

运算符	描述	示例
==	如果两个操作数的值相等，则条件为真。	(a == b)求值结果为 false
!=	如果两个操作数的值不相等，则条件为真。	(a != b)求值结果为 true
>	如果左操作数的值大于右操作数的值，则条件成为真。	(a > b)求值结果为 false
<	如果左操作数的值小于右操作数的值，则条件成为真。	(a < b)求值结果为 true
>=	如果左操作数的值大于或等于右操作数的值，则条件成为真。	(a >= b)求值结果为 false
<=	如果左操作数的值小于或等于右操作数的值，则条件成为真。	(a <= b)求值结果为 true

实例

假设变量a的值是10，变量b的值是21，参考以下代码实现 -

#!/usr/bin/python3
#coding=utf-8
# save file : comparison_operators_example.py

a = 21
b = 10

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 less than b" )
else:
   print ("Line 3 - a is not less than b")

if ( a > b ):
   print ("Line 4 - a is greater than b")
else:
   print ("Line 4 - a is not greater than b")

a,b=b,a #values of a and b swapped. a becomes 10, b becomes 21

if ( a <= b ):
   print ("Line 5 - a is either less than or equal to  b")
else:
   print ("Line 5 - a is neither less than nor equal to  b")

if ( b >= a ):
   print ("Line 6 - b is either greater than  or equal to b")
else:
   print ("Line 6 - b is neither greater than  nor equal to b")

将上面代码保存到文件： comparison_operators_example.py 中，执行结果如下 -

F:\worksp\python>python comparison_operators_example.py
Line 1 - a is not equal to b
Line 2 - a is not equal to b
Line 3 - a is not less than b
Line 4 - a is greater than b
Line 5 - a is either less than or equal to  b
Line 6 - b is either greater than  or equal to b

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