Question

我是新手尝试使用LPTH学习python。我试图以不同的方式做运动21。我没有将值放在变量中，而是要求用户输入值。

def add(a,b):
    print "Add %d and %d." %(a,b)
    print a+b

def substract (a,b):
    print "Substract %d from %d." %(a,b)
    print a-b

def multiply (a,b):
    print "Multiply %d*%d." %(a,b)
    print a*b

def divide (a,b):
    print "Dividing %d and %d." %(a,b)
    print a/b

total_age_of_the_class = add(int(raw_input(">")) , int(raw_input(">")))
#height_difference = substract (int(raw_input("Ram's height:"), int(raw_input("Shyam's height:"))))
height = substract (78,4)
weight = multiply (90,2)
iq = divide (100,2)

print "Age:%d, height:%d, weight:%d, iq:%d" %(total_age_of_the_class, height, weight, iq)

由于某种原因，当代码运行代码的最后一行时会抛出错误。在此先感谢您的帮助。

Answer 1

你应该返回你的功能的结果，而不是打印它们：

def substract (a,b):
    print "Substract %d from %d." %(a,b)
    return a-b

def multiply (a,b):
    print "Multiply %d*%d." %(a,b)
    return a*b

def divide (a,b):
    print "Dividing %d and %d." %(a,b)
    return a/b

如果没有return statement，Python函数始终返回默认值None。这意味着当你到达这里时：

height = substract (78,4)
weight = multiply (90,2)
iq = divide (100,2)

height，weight和iq都将分配给None，这会导致字符串格式化操作因您的错误而失败。

Python TypeError：％d format：需要一个数字，而不是NoneType

1 个答案: