为什么计数器代码会在每次计数时添加额外的行？

Question

这个代码有什么问题 它每次向上或向下计数时都会添加额外的行 我怎样才能防止这种情况发生，以及为什么会发生这种情况

def counter(start, stop):
    x = start
    if start > stop:
        return_string = "Counting down: "
        while x >= stop:
            return_string += str(x)
            x = x-1 
            if start != stop:
                return_string += ","
            print(return_string)
    else:
        return_string = "Counting up: "
        while x <= stop:
            return_string += str(x)
            x = x + 1 
            if start != stop:
                return_string += ","
            print(return_string)
    return return_string

print(counter(1, 10)) # Should be "Counting up: 1,2,3,4,5,6,7,8,9,10"
print(counter(2, 1)) # Should be "Counting down: 2,1"
print(counter(5, 5)) # Should be "Counting up: 5"

Answer 1

使用以下命令：

def counter(start, stop):
    x = start
    if start > stop:
        return_string = "Counting down: "
        while x >= stop:
            return_string += str(x)
            x = x-1
            if start != stop:
                return_string += ","
        print(return_string)
    else:
        return_string = "Counting up: "
        while x <= stop:
            return_string += str(x)
            x = x + 1
            if start != stop:
                return_string += ","
        print(return_string)
    return return_string