每當我運行我創(chuàng)建的計算器程序時，它都可以正常工作，但文本“ None”一直顯示，我也不知道為什么。這是代碼：def add(): print 'choose 2 numbers to add' a=input('add this') b=input('to this') print a+b return menu()def sub(): print 'choose 2 numbers to subract' a=input('subract this') b=input('from this') print b-a return menu()def menu(): print "hello, Welcome" print "these are your options" print "1. add" print "2. sub"print menu()loop=2def sys(): while loop==2: a=input("please choose") if a==1: print add() elif a==2: print sub() else: return menu(),sys()print sys()這是輸出：hello, Welcomethese are your options1. add2. subNone <-------------------------(this is what I'm talking about)please choose如果它對任何人都有幫助，那么這是我完成的計算器的代碼（我粘貼它時看起來很混亂，但是當您復制和粘貼時它可以工作）def add(): print 'choose 2 numbers to add' a=input('add this') b=input('to this') print a+bdef sub(): print 'choose 2 numbers to subract' a=input('subract this') b=input('from this') print b-adef mul(): print 'choose 2 numbers to multiply' a=input("multiply this") b=input("by this") print b*adef div(): print 'choose what numbers your want to divide' a=input('divide this') b=input('by this') print a/bdef exp(): print 'choose your number you want to exponentiate' a=input('multiply this') b=input('by the power of this') print a**bdef menu(): print "hello, Welcome" print "these are your options" print "1. add" print "2. sub" print "3. mul" print "4. div" print "5. expo" print "0. to end"menu()
1 回答
一只甜甜圈
TA貢獻1836條經(jīng)驗 獲得超5個贊
那是因為該函數(shù)menu()沒有返回任何東西，默認情況下，python中的一個函數(shù)會返回None
>>> def func():pass
>>> print func() #use `print` only if you want to print the returned value
None
只需使用：
menu() #no need of print as you're already printing inside the function body.
從和sys()刪除后的新版本。不必在每個函數(shù)內(nèi)部使用，只需在其末尾調(diào)用該函數(shù)即可。return menu()add()sub()return menu()menu()while loop
def sys():
while True:
a = input("please choose")
if a == 1:
add() # call add(), no need of print as you're printing inside add() itself
elif a==2:
sub()
menu() # call menu() at the end of the loop
while loop==2實際上loop==2首先計算表達式，如果是，True則while loop繼續(xù)，否則立即中斷。在您的情況下，因為您不更改loop變量的值，所以可以簡單地使用while True。
>>> loop = 2
>>> loop == 2
True
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