Description and usage of nonlocal keyword in python

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Description

1. The variables declared by nonlocal are not local or global variables, but variables in external nested functions.

2. The variables defined by nonlocal will only play a role in the called subfunctions.

Example

X = 1def func (): nonlocal x x = 2 print (x) func () print (x) result code error, SyntaxError: no binding for nonlocal'x 'found

Why did I just change global to nonlocal and report it wrong? Because nonlocal is a function used in a function.

X = 1def func (): X = 2 def subfunc (): nonlocal x x = x + 1 print ('value printed within subfunc:% d'% x) return x print (value printed in 'func:% d'% x) return subfuncfunc () print (value printed outside func:% d'% x) the result is: value printed within func: value printed outside 2func: 1

The nonlocal keyword does not change the value of either the global variable xroom1 or the local variable xroom2. This means that the variables declared by nonlocal are not local or global variables.

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