python how come function sees external variables?

Question

def test1():
   print(x)

def test2(x):
   print(x)

x=1
test1()
test2(x)

When I run this python code, I get:

1

1

How can function test1 know about x, without passing it as an argument?

Answer 1

A variable which is defined in the main body of a file is called a global variable.

It will be visible throughout the file, and also inside any file which imports that file.

Read this

Here x is a global varaible.

try the below code

def test1():
    x=2
    print(x)


def test2(x):
   print(x)

x=1
test1()
test2(x)

Here the output will be

2
1

Because test1 will print its local variable x.

You can use global keyword to modify the value of global variable x in test1()

def test1():
    global x
    x=2
    print(x)


def test2(x):
   print(x)

x=1
test1()
test2(x)

Output

2
2