Why this code returns an unexpected "None" ?

Question

Code:

vvod = input()
x = vvod.split(" ")

def sum(x):
print(int(x[0]) + int(x[2]))

def minus(x):
print(int(x[0]) - int(x[2]))

def mn(x):
print(int(x[0]) * int(x[2]))

def delit(x):
print(int(x[0])/int(x[2]))

def procent(x):
print(int(x[0])/int(x[2])*100)

def procent2(x):
print(int(x[0])*int(x[2])/100)

def stepen(x):
print(int(x[0])**int(x[2]))

if x[1] == "+":
print(sum(x))
elif x[1] == "-":
print(minus(x))
elif x[1] == "*":
print(mn(x))
elif x[1] == ":":
print(delit(x))
elif x[1] == "%":
print(str(procent(x))+"%")
print("ввод: x , % , y ")
print("вывод: сколько % составляет x от y")
elif x[1] == "**":
print(stepen(x))
print("ввод: число, ** , степень")
elif x[1] == "%%":
print(procent2(x))
print("ввод: число , %% , процент")
print("вывод: сколько процент составляет от числа")
else:
print("can't operate!")

Answer 1

None of the defined functions return a value. The main routine tries to print the return value from each function, but of course it has none to print.

I recommend replacing the print statements that are inside the functions with return statements, and let the main code do all the printing.

For example,

def minus(x):
return int(x[0]) - int(x[2])

Answer 2

Brian
The given code will print the expected result except there is a None following.

I made a code about return weeks before, but now decided to expand it to cover the issue ?????? is facing.

https://code.sololearn.com/cVF03G3wAXBt/?ref=app

Answer 3

Wong Hei Ming you are correct. I did not mention that, as the OP did not seem confused about why the results were being printed.