1. Global scope value can not be changed in function.
2. We can define a global variable in a function by using global.
3. Rules of using variable:
- First start with the local scope, if any. If the variable is defined here, use the value.
- Look at any enclosing scopes, starting with the innermost. These are "outside" local scopes. If the variable is defined in any of them, use the value.
- Look in the global scope. If the variable is there, use the value.
- Finally, look in the built-in functions.
- If no value is found, an error will be thrown.
Regular Expression(for extract number from a long string):
1.
Python 学习5
原文：http://www.cnblogs.com/kingoscar/p/5930012.html
