Python20 of global and local variables

First, local and global variables

　　Local variables: the variables in the function body refers to the definition of the scope of the internal function body only

　　Global Variables: variable refers vitro function definition, the scope is the whole code segment

Therefore, in vivo function can directly access the global variables can not access the local variables in the function vitro

Second, modify global variables in the function body

　　When the function body to modify global variables, Python automatically generates a name as a local variable with global variable, so as to achieve protection of global variables (not change the value of a global variable in the operation of the function body), but can be use global keyword in a local variable, global variable modifications , as follows

1 x = 1
2 def function():
3     x = 5
4     print(x)
5 
6 >>> function()
7 5
8 >>> print(x)
9 1

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global keyword

 1 x = 1
 2 def function():
 3     globals x
 4     x = 5
 5     print(x)
 6 
 7 function()
 8 5
 9 >>> x
10 5

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