[ASK-PYTHON]Some problem with parameter

[D̉̋ilẻ̡̓t͓tant͖͑̓e]

So, I recently learn pyhon and stuck at defining parameters
I mean the variables that defined in the parameters can't work in others

Here's an example:

def add(a,b):
	print a,"+",b,"=",a+b

def inputnum():
	a=input("First number: ")
	b=input("Second number: ")

inputnum()
add(a,b)

Any help will be appreciated

[MadVillain]

Variables have what's called scope. When variables are defined in the context of a function like you've done, they have no meaning outside of that function. You can however define these as global variables which exist outside of either function where they are visible to both functions and any future functions you make. You can fix your code like this but don't get used to using global variables often:

def add(a,b):
	print a,"+",b,"=",a+b

def inputnum():
	global a
	global b
	a=input("First number: ")
	b=input("Second number: ")

inputnum()
add(a,b)

[D̉̋ilẻ̡̓t͓tant͖͑̓e]

Thank you so much
I almost manually put the input in every other function

But why I shouldn't get used to using global variables?

[MadVillain]

Global variables are a lot harder to keep track of. For instance you could run one function that is expecting a global variable to be consistent and if another function happens to change that variable it will fuck up the result from the other function. This is pretty trivial in your code, there's not much to keep track of, but in large systems where no one person actually knows everything going on in the code, you want to avoid global variables.

[Cir]

I'm just learning myself, so feel free to berate me if I've done something wrong, but this code avoids using global variables, it also uses raw_input instead of input which makes error handling easier, and it of course turns the strings a and b into integers before it adds them. Otherwise if A is 3 and B is 4, it will print the string assigned to a, and the string assigned to b, one after the other, which is 34. You do get errors if you enter something other than an integer, but that's easily avoided.

a = 0
b = 0
def add(a,b):
	print a,"+",b,"=",a+b

def inputnum(a, b):
	a=raw_input("First number: ")
	b=raw_input("Second number: ")
	return a, b
    
a, b = inputnum(a,b)
a = int(a)
b = int(b)
add(a,b)

[Rich White Male]

I was wondering the same thing myself...