Python while true 语句 - 不会将输入作为变量使用

Question

我正在尝试从任一选项中获取变量 start_date 和 end_date，以便稍后在我的程序中使用。但是代码也没有return。 start_date 和 end_date 的值仍然是之前输入的值，仍在内存中。任何想法如何解决？谢谢

def dateChoices():
    while True:
        print("Menu")
        print("1.All Dates")
        print("2.Selected Dates")
        print("3.Exit")
        choice=int(input("Enter your choice:"))


        if choice==1:
            start_date = ManagerAll['Min_Date'][0]  
            end_date = ManagerAll['Max_Date'][0]   
            print("All dates chosen" +str(start_date))
            return start_date, end_date
            break

        elif choice==2:
            start_date = input('enter a start date (format is YYYY-MM-DD):')
            start_date = pd.to_datetime(start_date, format='%Y-%m-%d')
            end_date = input('enter an end date (format is YYYY-MM-DD):')
            end_date = pd.to_datetime(end_date, format='%Y-%m-%d')
            print('start date chosen is' +str(start_date))
            print('end date chosen is' +str(end_date))
            return start_date, end_date
            break

        elif choice==3:
            break
        else:
            print("Wrong Choice")

    print(start_date)
    print(end_date)

    print(end_date)

Answer 1

有几处需要更改

缩进 - while 循环在函数之外
return
当一个函数是 returning 值时，需要在变量中捕获它们。

我已经进行了这些更改，希望这就是您所期待的

import pandas as pd

def dateChoices():
    while True:
        print("Menu")
        print("1.All Dates")
        print("2.Selected Dates")
        print("3.Exit")
        choice=int(input("Enter your choice:"))
    
        if choice==1:
            start_date = ManagerAll['Min_Date'][0]  
            end_date = ManagerAll['Max_Date'][0]   
            print("All dates chosen" +str(start_date))
            return start_date, end_date
    
        elif choice==2:
            start_date = input('enter a start date (format is YYYY-MM-DD):')
            start_date = pd.to_datetime(start_date, format='%Y-%m-%d')
            end_date = input('enter an end date (format is YYYY-MM-DD):')
            end_date = pd.to_datetime(end_date, format='%Y-%m-%d')
            return start_date, end_date
    
        elif choice==3:
            break
        else:
            print("Wrong Choice")
sd, ed = dateChoices() 
print('start date chosen is ' +str(sd))
print('end date chosen is ' +str(ed))

输出

Menu
1.All Dates
2.Selected Dates
3.Exit
Enter your choice:2
enter a start date (format is YYYY-MM-DD):2001-04-15
enter an end date (format is YYYY-MM-DD):2002-09-09
start date chosen is 2001-04-15 00:00:00
end date chosen is 2002-09-09 00:00:00
>

Python while true 语句 - 不会将输入作为变量使用

Python while true statement - will not take the input as a variable to use

python

while-loop

dataframe

pandas