_ What are the application scenarios in Python

1. 1000_000_000 Split numbers , Let people quickly see how many digits there are
2. be used for for loop
   for i in range(1000) And for _ in range(1000), If you just control the loop and don't use variables later i In terms of , use _ More efficient .

python Private variable does not exist in , If there are properties in the class that need to be protected , Then you can prefix the attribute with two underscores , The actual name of the attribute is hidden （ Of course it was just renamed , There is still a way to access , But at least IDE Don't show it directly in , You can't misuse it if you don't use it intentionally ）