强制用户在 Python 中只输入 Y 或 N

Question

我是编程新手，我的第一个评估是创建一个向用户提出几个问题的程序。 第一个问题要求用户回答 Y 或 N，我想强制用户只做它，不断问他们同样的问题，直到用户输入 Y 或 N，不接受任何其他字母或数字或符号。 如果答案是 N，那么用户会被问到另一个问题（这显然对我有用）等等。

我正在尝试使用 while 循环，现在我迷路了：

print("Phase vaccine rollout (PVR) v1.0")
print("==========================")

phase1a = input("Are you a quarantine and border worker,\n\
prioritised frontline healthcare worker, or\n\
an aged care/disability care staff member or resident (Y/N)?: ")

while phase1a.upper() == "Y" or "N":

 if phase1a.upper() == "Y":
     print()
     print("Vaccines will be made available to you in Phase 1a")
     print()
     exit()

 elif phase1a.upper() == "N":
     print("__________________________")
     phase1b = input("Are you a health care worker, or\n\
a critical or high risk worker (including defence,\n\
police, fire, emergency services and meat processing (Y/N)?: ")
     continue

 else:
     break

# --- 从这里我将继续阶段1b ...

谢谢！

Answer 1

而不是while phase1a.upper() == "Y" or "N": ，你可以写：

while phase1a.upper() != "Y" and phase1a.upper() != "N":
  print("Invalid input. Please enter "Y" or "N".)
  phase1a = input("Are you a quarantine and border worker,\n\
  prioritised frontline healthcare worker, or\n\
  an aged care/disability care staff member or resident (Y/N)?: ")

您将不得不稍微重组您的if语句，但希望这可以向您展示这个想法。 这将迫使用户继续输入，直到他/她输入“Y”或“N”。

Answer 2

使用while True循环可以解决问题....

print("Phase vaccine rollout (PVR) v1.0")
print("==========================")

while True:
 phase1a = input("Are you a quarantine and border worker,\n\
prioritised frontline healthcare worker, or\n\
an aged care/disability care staff member or resident (Y/N)?: ")
 if phase1a.upper() == "Y":
     print()
     print("Vaccines will be made available to you in Phase 1a")
     print()
     exit()

 elif phase1a.upper() == "N":
     print("__________________________")
     phase1b = input("Are you a health care worker, or\n\
a critical or high risk worker (including defence,\n\
police, fire, emergency services and meat processing (Y/N)?: ")
     exit()
 else:
     continue

# --- and from here I will continue with the phase1b...

Answer 3

我们将使用 while True ，它将以 else 语句结束，如果不是 Y/N，它将要求用户重复他们的输入。 另请注意：如果用户输入 N，则必须添加结果。

print("Phase vaccine rollout (PVR) v1.0")
print("==========================")

phase1a = input("Are you a quarantine and border worker,\n\
prioritised frontline healthcare worker, or\n\
an aged care/disability care staff member or resident (Y/N)?: ")

while  True:

    if phase1a.upper() == "Y":
    
        print("\nVaccines will be made available to you in Phase 1a\n")
   
        exit()

    elif phase1a.upper() == "N":
        print("__________________________")
        phase1b = input("Are you a health care worker, or\n\
        a critical or high risk worker (including defence,\n\
        police, fire, emergency services and meat processing (Y/N)?: ")
        break

   else:
       phase1a = input("\nAre you a quarantine and border worker,\n\
       prioritised frontline healthcare worker, or\n\
       an aged care/disability care staff member or resident (Y/N)?: ")