stay Python We often see that when running a program, there will always be if __name__ == "__main__" This code . We know , stay Java There will be one main Method , When we run the program , Just run one individual main The method can , stay python It's the same with China ,,“if __name__==’__main__:” Like A sign , Symbolize Java And other languages , Tell the programmer , The code entry is here . Let's show you through the code ：
# modular 01
from demo_02 import *
a = 50
print(" Little ")
print(a)
# 02 modular
b = 100
print(" This is the module 02")
print(b)Running results ：
But sometimes ,02 Part of the code of the module doesn't want to run directly 01 Module runs directly , The following changes are made ：
# modular 01
from demo_02 import *
a = 50
print(" Little ")
print(a)
# 02 modular
b = 100
print(" This is the module 02")
if __name__ =="__main__" :
print(b)Now let's have a look , Running results ：
We found no input 100, Description is running 01 When the module ,print(b) This code does not run .
Let's continue with the demonstration ：
from demo_02 import *
# modular 01
a = 50
print(" Little ")
print(a)
print(' modular A in __name__ Value ：{}'.format(__name__))# 02 modular
b = 100
print(" This is the module 02")
print(b)
print(' modular 02 in __name__ Value ：{}'.format(__name__))When we run 02 When the module ：
And when we run 01 When the module ：
comparison , function 02 when __name__ The value is :__main__; function 01 when ,02 Module __name__ The value is :__demo_02, So I found ： When which module is executed directly , The module “__name__” The value is “__main__”, The first mock exam is imported into another module. ,“__name__” The value of is the real name of the module .
therefore , When running “if __name__=='__main__':” When the sentence is , If the current module is directly executed ,__name__ The value is __main__, The result of conditional judgment is True,“if __name__=='__main__':” The following code block will be executed .
