阻止命令运行

Question

如果用户输入“no”来打印（M1），如何停止最后一个print语句的运行？我希望程序在打印M1时完成。我得到了错误 由于在if块中声明“TaxCode”，用户输入“no”时出现“NameError:未定义名称“TaxCode”。 非常感谢。你知道吗

name = input("What is your name? ")
while True:
    try:
        income = int(input("What is your income? ($) "))
        break
    except ValueError:
        print ("Invalid input\nPlease enter a figure")
        continue
    else:
        break

M1  = "This program cannot determine your tax code. Please use the program for secondary income "

print("Please answer the questions with 'yes' and 'no'")


Q1=input("Do you receive an income tested benefit? ")
while Q1 != "yes" and Q1 != "no":
    print("\nPlease enter either 'yes' or 'no'")
    Q1=input("Do you recieve an income tested benefit? ")
    if Q1=="yes":
                 Q2=input("Is this tax code for the income tested benefit? ")
                 while Q2 != "yes" and Q2 != "no":
                     print("\nPlease enter either 'yes' or 'no'")
                     Q2=input("Is this tax code for the income tested benefit? ")
                      if Q2=="yes":
                                TaxCode = "M"
                      elif Q2=="no":
                                  print (M1)

print("Thanks for answering the questions.",name,"Your tax code is ",TaxCode)

Answer 1

在if语句之前用空值定义TaxCode，以防止NameError。这样TaxCode =''

您可以使用exit(0)终止程序，这里的数字（）表示成功/失败。与linux中的退出状态相同。所以你的代码是

while Q1 != "yes" and Q1 != "no":
    print("\nPlease enter either 'yes' or 'no'")
    Q1=input("Do you recieve an income tested benefit? ")
    if Q1=="yes":
        Q2=input("Is this tax code for the income tested benefit? ")
         while Q2 != "yes" and Q2 != "no":
             print("\nPlease enter either 'yes' or 'no'")
             Q2=input("Is this tax code for the income tested benefit? ")
             TaxCode='' #define it before using
             if Q2=="yes":
                 TaxCode = "M"
             elif Q2=="no":
                  print (M1)
                  exit(0) # terminates program and raises success non-zero value refers failure.

print("Thanks for answering the questions.",name,"Your tax code is ",TaxCode)

如果在函数中使用上述代码，并且希望停止函数，则可以使用return语句通过返回None跳过最后一行的打印，因此在这种情况下，您的代码将被删除。你知道吗

while Q1 != "yes" and Q1 != "no":
    print("\nPlease enter either 'yes' or 'no'")
    Q1=input("Do you recieve an income tested benefit? ")
    if Q1=="yes":
        Q2=input("Is this tax code for the income tested benefit? ")
         while Q2 != "yes" and Q2 != "no":
             print("\nPlease enter either 'yes' or 'no'")
             Q2=input("Is this tax code for the income tested benefit? ")
             TaxCode='' #define it before using
             if Q2=="yes":
                 TaxCode = "M"
             elif Q2=="no":
                  print (M1)
                  return None # skips print and returns to calling function.
print("Thanks for answering the questions.",name,"Your tax code is ",TaxCode)

您可以根据您的逻辑使用exit或return，因为您不清楚这段代码是用在函数中还是用在main中，我解释了两者。你知道吗

Answer 2

您应该在if语句之外定义“TaxCode”。你知道吗

例如

TaxCode = ""
Q1=input("Do you receive an income tested benefit? ")
while Q1 != "yes" and Q1 != "no":
    print("\nPlease enter either 'yes' or 'no'")
    Q1=input("Do you recieve an income tested benefit? ")
if Q1=="yes":
                 Q2=input("Is this tax code for the income tested benefit? ")
                 while Q2 != "yes" and Q2 != "no":
                     print("\nPlease enter either 'yes' or 'no'")
                     Q2=input("Is this tax code for the income tested benefit? ")
                 if Q2=="yes":
                                TaxCode = "M"
                 elif Q2=="no":
                                  print (M1)

print("Thanks for answering the questions.",name,"Your tax code is ",TaxCode)

Answer 3

就像@Navieclipse提到的那样，在使用之前需要定义TaxCode。你知道吗

name = input("What is your name? ")
while True:
    try:
        income = int(input("What is your income? ($) "))
        break
    except ValueError:
        print ("Invalid input\nPlease enter a figure")
        continue
    else:
        break

TaxCode = ""
M1  = "This program cannot determine your tax code. Please use the program for secondary income "

print("Please answer the questions with 'yes' and 'no'")

while True:
    Q1=input("Do you receive an income tested benefit? ")
    if Q1 == "yes":
        Q2=input("Is this tax code for the income tested benefit? ")
        if Q2 == "yes":
            TaxCode = "Test"
            print("Thanks for answering the questions, "+ name + ", " + "your tax code is " + TaxCode + ".")
            break
        elif Q2 == 'no':
            print(M1)
            break
    else:
        print("\nPlease enter either 'yes' or 'no'")

另外，在这里复制之后格式化它会使它更容易阅读。你知道吗