函数内的输入[重复]

Question

我做了一个ATM功能程序，我需要帮助，因为我无法在我的程序中显示我的用户名（un）和密码（pw），错误是

NameError: name 'un' is not defined

我尝试在第一行定义 un ，但用户输入信息后该值没有改变。

#functions
def FWelcome():
    print("WELCOME!")
    print("Please Log-In to access ATM:")
    return;

def FUsername():
    while True:
        un=input("\nEnter Username ( use only letters ):")
        if un.isalpha():
            break
        else : #invalid
            print ("Invalid Username. Use of symbols and/or numbers are not allowed.\n")
    return;

def FPassword():
    while True:
        pw=input("Enter Password ( use only numbers ):")
        if pw.isnumeric():
            break
        else : #invalid
            print ("Invalid Password. Use of symbols and/or letters are not allowed.\n")
    return;

#atm program
FWelcome()

#username
FUsername()

#password
FPassword()

print("\nHello! Your Username is ", un, " and your password is ",pw )

Answer 1

你应该返回值：

def FUsername():
    while True:
        un=input("\nEnter Username ( use only letters ):")
        if un.isalpha():
            break
        else : #invalid
            print ("Invalid Username. Use of symbols and/or numbers are not allowed.\n")
    return un

def FPassword():
    while True:
        pw=input("Enter Password ( use only numbers ):")
        if pw.isnumeric():
            break
        else : #invalid
            print ("Invalid Password. Use of symbols and/or letters are not allowed.\n")
    return pw

#atm program
FWelcome()

#username
un = FUsername()

#password
pw = FPassword()

Answer 2

un 在FUsername 内部定义，因此无法全局访问。您要么必须将“print un”语句放在函数内，要么使用全局默认虚拟值声明它，然后在 FUsername 中更新它

Answer 3

您在函数内部声明 un，但尝试在该函数外部访问它。解决此问题的一种方法是返回值。另一种方法是使变量成为全局变量。

#Comment the 2 below lines out if you want to return the variables from the function.
un=input("\nEnter Username (use only letters ):")
pw=input("Enter Password ( use only numbers ):")
def FWelcome():
    print("WELCOME!")
    print("Please Log-In to access ATM:")
    return;

def FUsername():
    while True:
        #Comment this out if you want to declare it globally
        un=input("\nEnter Username ( use only letters ):")
        if un.isalpha():
            break
        else : #invalid
            print ("Invalid Username. Use of symbols and/or numbers are not allowed.\n")
    return un

def FPassword():
    while True:
        #Comment this out if you want to declare it globally.
        pw=input("Enter Password ( use only numbers ):")
        if pw.isnumeric():
            break
        else : #invalid
            print ("Invalid Password. Use of symbols and/or letters are not allowed.\n")
 #Or return the variable un
    return pw

#atm program
FWelcome()

#username
FUsername()

#password
FPassword()



print("\nHello! Your Username is ", un, " and your password is ",pw )