如何從python中的另一個變量中減去一個變量

import easygui as eg 
import sys 

version = 'Percentage Calculator' 

Options = [ 'Percantage Increase', 'Percentage Decrease' ] 

button = eg.buttonbox ('What would you like to calculate', title = version, choices =  Options) 

if button == Options [0]: 
    enter = eg.enterbox ('Please enter a number between 0 and 999.', title = version,  strip=False) 
    if enter < '0' or enter > '999': 
      eg.msgbox ('please choose a number between 0 and 999.', title = version,  ok_button='OK') 
      sys.exit() 
    enter2 = eg.enterbox ('please enter a number between 0 and 999, that is bigger than  the first number.', title = version, strip=False) 
    if enter2 < '0' or enter2 > '999': 
      eg.msgbox ('please choose a number between 0 and 999.', title = version,  ok_button='OK') 
      sys.exit() 
    elif enter2 < var enter: 
      eg.msgbox ('please choose a number bigger than the first number.', title =  version, ok_button='OK') 
      sys.exit() 
    Subtract = enter2 - enter 
    print (Subtract)

這是我的代碼......正如你可以看到的，在底部附近，它說'enter2 - enter'我希望這個減去用戶的第二個數字把從第一號，但它只是說...如何從python中的另一個變量中減去一個變量

Traceback (most recent call last): 
    File "C:\Users\olitr_000\Desktop\PYTHON\Percentage Calculator\Percentage  Calculator.py", line 22, in <module> 
    Subtract = enter2 - enter 
TypeError: unsupported operand type(s) for -: 'str' and 'str'

我能做些什麼，這樣說進入1等於55和ENTER2 = 198我怎麼會得到它，這樣它198 - 55？

請幫助，我需要任何更多的信息，請通知我。

來源

2014-06-22 olitr20

您需要將輸入轉換爲'int'，因爲它們是字符串默認情況下。 'int（enter）'和'int（enter2）' – karthikr

請注意，代碼中存在更多問題。如'enter2 <'0'或enter2>'999'檢查將無法正常工作。在進行這些檢查之前，您必須轉換爲「int」 – karthikr

您的問題是，通過使用eg.enterbox功能，數字用戶輸入將被視爲字符串。爲了解決這個問題，我們把輸入框返回的'string'發送給int（）函數。這會將數字字符串轉換爲可用於減去其他整數的實際整數。

例如。

enter = "3" 
enter = int(enter) 
enter2 = "4" #This is an example of what the variable looks like coming from the enterbox 
enter2 = int(enter2) #enter2 now looks like 4 instead of "4" 

output = enter2 - enter #this will return 1 to the variable output

希望這有助於;）

哦，你並不需要在此行中的引號：

if enter < '0' or enter > '999':

，你是在說 '0' 是一個字符串，而不是像數字一樣處理;）

來源

2014-06-22 08:33:45 seekjet

你不能減去兩個字符串，先將它們轉換爲整數。

Subtract = int(enter2) - int(enter)

來源

2014-06-22 08:18:56 jabaldonedo

這會幫助你。

import easygui as eg 
import sys 

version = 'Percentage Calculator' 

Options = [ 'Percantage Increase', 'Percentage Decrease' ] 

button = eg.buttonbox ('What would you like to calculate', title = version, choices =  Options) 

if button == Options [0]: 
    enter = eg.enterbox ('Please enter a number between 0 and 999.', title = version,  strip=False) 
    if enter < '0' or enter > '999': 
      eg.msgbox ('please choose a number between 0 and 999.', title = version,  ok_button='OK') 
      sys.exit() 
    enter2 = eg.enterbox ('please enter a number between 0 and 999, that is bigger than  the first number.', title = version, strip=False) 
    if enter2 < '0' or enter2 > '999': 
      eg.msgbox ('please choose a number between 0 and 999.', title = version,  ok_button='OK') 
      sys.exit() 
    elif enter2 < var enter: 
      eg.msgbox ('please choose a number bigger than the first number.', title =  version, ok_button='OK') 
      sys.exit() 
    Subtract = int(enter2) - int(enter) 
    print (Subtract)

來源

2014-06-22 08:20:42 DOSHI

我認爲這是你面對這裏只是parsing問題，因爲我們知道，Python不只是從鍵盤string值接受，因爲在它的代碼沒有變量類型定義，這就是爲什麼我們總是需要將輸入轉換或解析爲適當的類型。

>>> a = "3.14" 
>>> float(a) 
3.14 
>>> int(float(a)) 
3

來源

2014-06-22 08:29:41 wisdom

如何從python中的另一個變量中減去一個變量

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