Python入门100题之024：实现sum函数

题目：

实现一个sum()函数

视频教程：

Python入门100题之024：实现sum函数

代码1：

def mysum(*args):
    if (len(args) == 1 and
       isinstance(args[0], list)):
        args = args[0]
    total = 0
    for item in args:
        total += item
    return total


print(mysum([1, 2, 3]))
print(mysum(1, 2, 3))

代码2：

class MySum:
    def __call__(self, *args):
        if (len(args) == 1 and
           isinstance(args[0], list)):
            args = args[0]
        total = 0
        for item in args:
            total += item
        return total


mysum = MySum()
print(mysum([1, 2, 3]))
print(mysum(1, 2, 3))

代码3：

def mysum(*args):
    if len(args) == 1 and isinstance(args[0], list):
        args = args[0]
    total = 0
    for item in args:
        if isinstance(item, (int, float)):
            total += item
        else:
            total += float(item)
    return total


print(mysum([1, 2, '3.4']))
print(mysum(1, 2, '3.4'))