关于用for循环求和

Question

我试图让用户输入出生日期，然后在这些数字中添加各个整数。此外，如果这些数字中的任何一个的总和大于或等于 10，则循环会重复，并且该过程会针对该值再次运行。到目前为止，这是我的代码，

if (sumYear >= 10):
    sumYear2=0
    for num in str(sumYear):
        sumYear2 += int(num)
print(sumYear2)

这有效，但我认为最好将其作为循环来完成。如果有某种方法我不必使用像 sumYear2 这样的东西，那就太好了。请注意，我认为我无法使用 sum() 函数。

谢谢大家的帮助。不过我有一个问题。我不知道为什么当我提供月份 02 和日期 30 时这段代码没有被评估

while True:
        year=input("Please enter the year you were born: ")
        month=input("Please enter the month you were born: ")
        day=input("Please enter the day you were born: ")
        if(int(month)==2 and int(day)<=29):
            break
        elif(int(month)==1 or 3 or 5 or 7 or 8 or 10 or 12 and int(day)<=31 ):
            break
        elif(int(month)==4 or 6 or 9 or 11 and int(day)<=30):
            break
        else:
            print("Please enter a valid input")

Answer 1

工作量太大了。

singledigitsum = (int(inputvalue) - 1) % 9 + 1

请注意，对于小于 1 的数字，此操作将会失败。

Answer 2

@Ignacio Vazquez-Abrams 的答案提供了公式。但是，如果没有，那么您的代码作为不使用 sumYear2 的循环可能如下所示：

while sumYear >= 10:
      sumYear = sum(map(int, str(sumYear)))

如果您不允许使用 sum （作业），那么：

while sumYear >= 10:
      s = 0
      for d in str(sumYear):
          s += int(d)
      sumYear = s

---

对于第二个假设 Python 3 的问题：

while True:
    try:
        year  = int(input("Please enter the year you were born: "))
        month = int(input("Please enter the month you were born: "))
        day   = int(input("Please enter the day you were born: "))
        birthday = datetime.date(year, month, day)
    except ValueError as e:
        print("error: %s" % (e,))
    else:
        break

---

如果不允许使用 try/ except 那么：

year  = get_int("Please enter the year you were born: ",
                datetime.MINYEAR, datetime.MAXYEAR)
month = get_int("Please enter the month you were born: ",
                 1, 12)
day   = get_int("Please enter the day you were born: ",
                1, number_of_days_in_month(year, month))
birthday = datetime.date(year, month, day)    

其中 get_int()：

def get_int(prompt, minvalue, maxvalue):
    """Get an integer from user."""
    while True:
        s = input(prompt)
        if s.strip().isdigit():
           v = int(s)
           if minvalue <= v <= maxvalue:
              return v
        print("error: the input is not an integer in range [%d, %d]" % (
            minvalue, maxvalue))

和 number_of_days_in_month()：

# number of days in a month disregarding leap years
ndays = [0]*13
ndays[1::2] = [31]*len(ndays[1::2])  # odd months
ndays[::2] = [30]*len(ndays[::2])    # even months
ndays[2] = 28 # February
ndays[8] = 31 # August 
# fill other months here ...

def number_of_days_in_month(year, month):
    return ndays[month] + (month == 2 and isleap(year))

Answer 3

你可以这样做

>>> d=123456
>>> sum(int(c) for c in str(d))
21