函数没有运行

Question

My functions in Python aren't returning values that I expect them to. Here is a MWE:

a = 6
b = 18
c = 0
def random_function(c):
    c = b/a
    return c

random_function(c)
print(c)

I expect this function to print 3, but instead it prints 0. I have just updated from 2.7 to 3.6 and this would have worked in 2.7 - what am I doing wrong?

Answer 1

Need to store returned value from method.

a = 6
b = 18
c = 0
def random_function(c):
    c = b/a
    return c

c= random_function(c)
print(c)

Answer 2

As @Dharmesh said, you need to store the value of c when it comes out of random_function() .

ie c = random_function(c)

The Reason:

Scope is everything. When you change the value of c from within the function, it only affects the value of c within the scope of that function and doesn't change its value in the global context.

In order for the value you assigned to c from within the function to be preserved, you need to assign c the value returned by the function.

Answer 3

you are printing c value which was assigned globally.

a = 6
b = 18
c = 0
def random_function(c):
    c = b/a
    return c    # -- this variable scope is local

random_function(c)
print(c)     #--  prints Global variable

to print as you expected, you need to change your function call like below

print (random_function(c))

or

c = random_function(c)  # this will re assign global value of 'c' with function return value 
print(c)