Python: using different variable names in function defination

Question

I'm very new to python and I have one question. In this code,

def abc(a,b,c):
        s = x+y+z
        q=(x+y+z)/2
        a = (q*(q-x)*(q-y)*(q-z))**0.5
        return (s,a)
  

print("Enter sides of a triangle")
x = float(input("a: "))
y = float(input("b: "))
z = float(input("c: "))
if x+y>z and x+z>y and y+z>x :
        print("Triangle is valid")
        tuple = abc(x,y,z)
else:
        print("Triangle is invalid")
print("PERIMETER and AREA OF TRIANGLE", tuple)

In the function definition of abc, I passed the variable names as a, b,c but I used them as x, y, z only and the output is also correct. Why this isn't showing any error? Is this correct?

Answer 1

It is not giving you an error, because you declared x , y and z as global variables and those are being used in your abc() function.

Answer 2

Inside abc() , the variables x , y and z are not local, but module-global.

If you put the rest of your code in another function, eg:

def tryit():
    print("Enter sides of a triangle")
    x = float(input("a: "))
    y = float(input("b: "))
    z = float(input("c: "))
    if x+y>z and x+z>y and y+z>x :
            print("Triangle is valid")
            tuple = abc(x,y,z)
    else:
            print("Triangle is invalid")
    print("PERIMETER and AREA OF TRIANGLE", tuple)

And then call tryit() , you'll get a NameError: name 'x' is not defined on the first line of abc() . That's because, this way, x , y and z are not global, but local to the tryit() function, so abc() has no visibility to them.