I cant find the source of my code printing 'none'-CodePudding

So I wrote this code and it works, however, I'm trying to find a way to make this code return the right output, as shown down below. Here is my code.

upto = 5
def original_num(upto:int):
    for x in range(1, upto 1):
        print (x, (7**x)%97)
def powerLoop(upto: int):
    upto = upto
    return original_num(upto)
print(powerLoop(upto))

But when I print the output, this is what I get...

But if I use print instead of return in the code,

upto = 5
def powerLoop(upto:int):
    for x in range(1, upto 1):
        print(x, (7**x)%97)
powerLoop(upto)

This is what I get,

How can I use return and then once I say print(powerloop(upto) the output will occur without printing 'none'?

CodePudding user response：

Your original_num(...) function already prints the desired output and returns None which you ultimately print in print(powerLoop(upto)).

Just:

powerLoop(upto)

will not print the return value, but still "harvest" the side-effects of the function calls (the other prints).

CodePudding user response：

Why you print again?

upto = 5
def original_num(upto:int):
    for x in range(1, upto 1):
        print (x, (7**x)%97)
def powerLoop(upto: int):
    return original_num(upto)

powerLoop(upto)

above, the last line, just cancel print, because your function original_num had already print the result.

and in python, if your function have nothing to return, it will return None, and then you print None.

def abc():
    a=100

print(abc())

above example will get None.

CodePudding user response：

If you want to write print(powerLoop(upto)) and don't get None you can use yield like below:

>>> upto = 5
>>> def powerLoop(upto:int):
...    for x in range(1, upto 1):
...        yield (x, (7**x)%97)
>>> print(*powerLoop(upto), sep='\n')
(1, 7)
(2, 49)
(3, 52)
(4, 73)
(5, 26)

>>> for ret in powerLoop(upto):
...    print(*ret)
1 7
2 49
3 52
4 73
5 26

If you want to use return you can use list and return list like below: (Edit answer base comment)

>>> upto = 5
>>> def powerLoop(upto:int):
...    out = []
...    for x in range(1, upto 1):
...        out.append([x, (7**x)%97])
...    return out

>>> print(*powerLoop(upto), sep='\n')
[1, 7]
[2, 49]
[3, 52]
[4, 73]
[5, 26]


>>> for ret in powerLoop(upto):
...    print(*ret)

1 7
2 49
3 52
4 73
5 26