Show Example 7

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小牛编辑

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2023-12-01

身份运算符比较两个对象的内存位置。有两个Identity运算符，如下所述 -

操作者	描述	例
is	如果运算符任一侧的变量指向同一对象，则求值为true，否则求值为false。	x是y，如果id（x）等于id（y），则结果为1。
is not	如果运算符两侧的变量指向同一对象，则求值为false，否则为true。	x不是y，如果id（x）不等于id（y），则不会产生1。

例子 (Example)

#!/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"

执行上述程序时，会产生以下结果 -

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