How to use a global variable in a Python function
In python, you could use global keyword to declare a variable inside a function as a global variable, such as: >>> global_var = 0 >>> def fun1(): global_var = 10 # global_var as local var print(global_var) >>> def fun2(): global global_var # declare global_var to be a global var global_var = 5 print(global_var) >>> print(global_var) 0 >>> fun1() 10 >>> print(global_var) 0 >>> fun2() 5 >>> print(global_var) 5 We define a global_var outside functions. Inside f un1() we define a local global_var without declaring it as global . Although it has the same name as the global_var outside the function, it is totally isolated from the gobal variable-- global_var . Inside fun2() , we declare global_var as a global variable, so it becomes global . First, we print global_var , it is 0. Then invoke fun1() , it prints the result of the local variable global_var . We then check the value of global_var , it is sti