如何在Python中的另一个函数中调用一个函数

Question

如您所见，我正在尝试制作货币转换器。 我要说的是，如果输入数字“ 1”，请转到函数“ gbp”。 它工作正常，直到到达询问您要转换多少钱的地方（第25行）。 当我键入一个值并按Enter时，它会产生一个回溯错误，告诉我第33、5和29行都具有“ +不支持的操作数类型：'float'和'str'”。

这是我的代码：

def start():
print("Hello and welcome to the very limited currency converter!\nIn this converter, the number '1' means Pounds Sterling, number '2' means US Dollars, '3' means Euros and '4' means Japanese Yen.")
From = input("Which currency do you wish to convert from?\n")
if From == ("1"):
    gbp()
    return
elif From == ("2"):
    usd()
    return
elif From == ("3"):
    euro()
    return
elif From == ("4"):
    yen()
    return
else:
    print("That is not a valid input. Please restart the program and input either '1', '2', '3' or '4'!")
return start

def gbp():
gbpTo = input("Which currency are you converting into?\n")
if gbpTo == ("1"):
    print("You are converting Pounds Sterling to Pounds Sterling... there is no conversion needed!")
elif gbpTo == "2":
    num = float(input("Please type in the amount of Pounds Sterling that you wish to convert into US Dollars.\n"))
    calc = num * 1.55
    float(calc)
    calc = round(calc, 2)
    print(num + " Pounds Sterling in US Dollars is $", + calc)
    return
start()

我将不胜感激。 谢谢

Answer 1

您正在尝试添加浮点数和字符串。 Python不知道您要添加哪种类型，因此您需要先将num和calc转换为字符串，然后再将其连接为字符串：

print(str(num) + " Pounds Sterling in US Dollars is $" + str(calc))

Answer 2

代替

print(num + " Pounds Sterling in US Dollars is $", + calc)

做

print("%f Pounds Sterling in US Dollars is $ %f" % (num, calc))