如果用戶沒有輸入某個單詞，則輸出錯誤信息

Question

這是我之前問過的一個問題的副本，但有點不同。

我是一個編程初學者（從來沒有編程過），我已經給了一個任務（學校）來製作一個程序，要求用戶提供一個形狀，然後根據給定的尺寸計算該形狀的體積用戶。但如果用戶沒有輸入「quit」，程序應該不斷詢問用戶形狀並繼續計算卷，並且當用戶輸入「quit」時，程序將假設打印出卷的列表計算。三個形狀是立方體，金字塔和橢圓體。

，例如，如果在立方體，立方體，棱錐，棱錐形，橢圓體，然後在用戶鍵入退出（與必要的尺寸沿着計算體積），則程序應該打印出：

立方體體積：4 ，5

金字塔卷：6,7

橢球體積：8

注：這些數字只是例如。

我已經成功（有點）讓程序注意到錯誤，並讓程序重複詢問用戶形狀和計算體積，直到輸入「quit」。但是，如果用戶沒有例如進入立方體，那麼最終的輸出應該是：

立方體體積：你有沒有做過任何計算多維數據集

金字塔卷：6,7

橢球卷：8

什麼，而不是我現在得到，這就是：

立方體的體積：[]

金字塔v olumes：6,7

橢圓形卷：8

有什麼辦法來實現正確的最終輸出？

這是我的代碼（這可能不是很大，但它是最好的，我現在可以做一個初學者，用那東西我們至今教授）：

#A program that allows the user to continuously pick different shapes and calculate their volumes. 

#import all functions from the math module. 

import math 
#allows the user to input the shape they want to calculate the volume of. Then that input is converted to all upper case 
#letters so that no matter what the user enters, it will be recognizable by the program. 
shape = input("please enter the shapes you want to calculate the volume of from cube, pyramid and ellipsoid, or Quit: ").upper() 

#Initializing the lists for the volumes of the three different shapes as empty lists so that it can be filled 
#later on. 
VolumeListCube = [] 
VolumeListPyramid =[] 
VolumeListEllipsoid = [] 

#defining the function that will calculate the volume of the cube and then adding them to the empty list VolumeListCube. 
def VolumeCube (sideLength): 
    volume = sideLength**3 
    #Adding the values to the list 
    VolumeListCube.append(volume) 
    #Sorting the values in the created list in ascending order 
    VolumeListCube.sort() 
    return; 

#defining the function that will calculate the volume of the pyramid and then adding them to the empty list VolumeListPyramid. 
def VolumePyramid (baseLength, height): 
    volume = round((1/3)*(baseLength**2)*height,1) 
    #Adding the values to the list 
    VolumeListPyramid.append(volume) 
    #Sorting the values in the created list in ascending order 
    VolumeListPyramid.sort() 
    return; 

#defining the function that will calculate the volume of the ellipsoid and then adding them to the empty list VolumeListEllipsoid. 
def VolumeEllipsoid (radius1, radius2, radius3): 
    volume = round((4/3)*math.pi*radius1*radius2*radius3,1) 
    #Adding the values to the list 
    VolumeListEllipsoid.append(volume) 
    #Sorting the values in the created list in ascending order 
    VolumeListEllipsoid.sort() 
    return; 

#The first while loop here checks if the user immediately inputs "Quit" or not, if they don't, then the next while loop is 
#executed, if they do input "Quit", then the program will print the require message. 
while shape != "QUIT": 
    #This is a infinte while loop since true is always true, this allows the error message at the end to be displayed 
    #and then loop back to the beginning of this loop, so that it can be executed again. 
    while True: 
     if shape in ["CUBE","PYRAMID","ELLIPSOID","QUIT"]: 
      #These if functions will allow the user to input shape parameters depending on what shape the user has chosen, then 
      #afterwards, another prompt is show for the user to choose another shape and input that shape's parameters. This will 
      #continue until the user inputs "Quit", then the required message will be printed and the volume results fot all the 
      #shapes chosen will be displayed in ascending order. 
      if shape == "CUBE": 
       sideLength = int(input("Please enter the length of the sides of the cube:")) 
       #recalling the function that calculates the volume of the cube. 
       VolumeCube (sideLength) 
       #lets the user to input another shape they want to calculate the volume of. 
       shape = input("please enter the shapes you want to calculate the volume of from cube, pyramid and ellipsoid, or Quit: ").upper() 
      elif shape == "PYRAMID": 
       baseLength = int(input("Please enter the base length:")) 
       height = int(input("Please enter the height:")) 
       # recalling the function that calculates the volume of the pyramid. 
       VolumePyramid (baseLength, height) 
       #lets the user to input another shape they want to calculate the volume of. 
       shape = input("please enter the shapes you want to calculate the volume of from cube, pyramid and ellipsoid, or Quit: ").upper() 
      elif shape == "ELLIPSOID": 
       radius1 = int(input("Please enter the first radius:")) 
       radius2 = int(input("Please enter the second radius:")) 
       radius3 = int(input("Please enter the third radius:")) 
       # recalling the function that calculates the volume of the ellipsoid. 
       VolumeEllipsoid (radius1, radius2, radius3) 
       #lets the user to input another shape they want to calculate the volume of. 
       shape = input("please enter the shapes you want to calculate the volume of from cube, pyramid and ellipsoid, or Quit: ").upper() 
      elif shape == "QUIT": 
       print ("\nYou have come to the end of the session.\nthe volume calculated for each shape are shown below:\n") 
       print("The volume of the cube(s) is:", VolumeListCube) 
       print("The volume of the pyramid(s) is:", VolumeListPyramid) 
       print("The volume of the ellipsoid(s) is:", VolumeListEllipsoid) 
       #This exits the program to stop repeated prints that would be caused due to the while loop 
       exit() 
     else: 
      print("Error, please enter a valid shape") 
      shape = input("please enter the shapes you want to calculate the volume of from cube, pyramid and ellipsoid, or Quit: ").upper() 

else: 
    print ("\nYou have come to the end of the session.\nYou have not performed any volume calculations") 

Answer 1

TL; DR

沒有時間去通過您的代碼，但我猜你所得到的最終結果爲list，所以

立方體的體積：[]

對此的快速轉義是使用if語句來檢查列表的大小是否爲0。即用戶沒有給出shape。

所以，一個簡單的：

print('cube volumes:',end=' ') 

#VolumeListCube is holding the final results 
if len(VolumeListCube) == 0: 
    print("You have not done any calculations for the cube") 
else : 
    #print your values as usual 

應該足夠了。編程