Python比較運算子範例

比較(關係)運算子比較它們兩邊的值，並確定它們之間的關係。它們也稱為關係運算子。假設變數a的值10，變數b的值是21，則 -

運算子	描述	範例
`==`	如果兩個運算元的值相等，則條件為真。	`(a == b)`求值結果為 `false`
`!=`	如果兩個運算元的值不相等，則條件為真。	`(a != b)`求值結果為 `true`
`>`	如果左運算元的值大於右運算元的值，則條件成為真。	`(a > b)`求值結果為 `false`
`<`	如果左運算元的值小於右運算元的值，則條件成為真。	`(a < b)`求值結果為 `true`
`>=`	如果左運算元的值大於或等於右運算元的值，則條件成為真。	`(a >= b)`求值結果為 `false`
`<=`	如果左運算元的值小於或等於右運算元的值，則條件成為真。	`(a <= b)`求值結果為 `true`

範例

假設變數a的值是10，變數b的值是21，參考以下程式碼實現 -

#!/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")

將上面程式碼儲存到檔案： comparison_operators_example.py 中，執行結果如下 -

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