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Python逻辑运算符示例

下表列出了所有Python语言支持的逻辑运算符。假设变量a持有10和变量b持有20,则:

运算符 描述 例子
and 所谓逻辑与运算符。如果两个操作数都为真,则条件为真。 (a and b) 为 true.
or 所谓逻辑OR运算符。如果有两个操作数都为非零,则条件变为真。 (a or b) 为 true.
not 所谓逻辑非运算符。用反转操作数的逻辑状态。如果条件为true,则逻辑非运算符将为false。 not(a and b) 为 false.

示例:

试试下面的例子就明白了所有的Python编程语言提供了逻辑运算符:

#!/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"
else:
   print "Line 5 - a and b are true"

当执行上面的程序它会产生以下结果:

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