提取函数

Question

我写了一个简单的程序，可以计算出给定数量的完美平方。我的代码是：

"""Print all the perfect squares from zero up to a given maximum.""" 

def main(): 
    """Even the main function needs a docstring to keep pylint happy""" 
    upper_bound = None 
    while upper_bound is None: 
     line = input("Enter the upper bound: ") 
     if line.isnumeric(): 
      upper_bound = int(line) 
     else: 
      print("You must enter a positive number.") 

    squares = [] 
    for num in range(2, upper_bound + 1): 
     for candidate in range(1, num): 
      if candidate * candidate == num: 
       squares.append(num) 

    print("The perfect squares up to {} are: ".format(upper_bound)) 
    for square in squares: 
     print(square, end=' ') 
    print() 

我想我的代码块提取成几个功能，我想出了我认为是一个可能的解决方案，但不幸的是我无法得到它的运行，因为它给了我一个错误unsupported operand type(s) for +: 'NoneType' and 'int'。我似乎无法找到这个问题的根源，我想知道我的解决方案是不是很糟糕，如果是的话，那么更好的解决方案是什么？

我尝试

"""Print all the perfect squares from zero up to a given maximum.""" 

    def read_bound(): 
    """Reads the upper bound from the standard input (keyboard). 
     If the user enters something that is not a positive integer 
     the function issues an error message and retries 
     repeatedly""" 


    line = input("Enter the upper bound: ") 
    if line.isnumeric() and int(line) >= 0: 
     upper_bound = int(line) 
    else: 
     print("You must enter a positive number.") 



    def is_perfect_square(num): 
    """Return true if and only if num is a perfect square""" 
    for num in range(2, upper_bound + 1): 
     for candidate in range(1, num): 
      if candidate * candidate == num: 
       return True 



    def print_squares(upper_bound, squares): 
    """Print a given list of all the squares up to a given upper bound""" 


    print("The perfect squares up to {} are: ". format(upper_bound)) 
    for square in squares: 
     print(square, end= ' ') 



    def main(): 
    """Calling the functions""" 
    upper_bound = read_bound() 
    squares = [] 
    for num in range(2, upper_bound + 1): 
     if is_perfect_square(num): 
      squares.append(num) 

    print_squares(upper_bound, squares) 


    main() 

Answer 1

您的代码有很多错误！我想你使用python 3.x！我用python 2.7重写了一些代码！只需发布代码如下！如果你不能运行它，请让我知道！

"""Print all the perfect squares from zero up to a given maximum.""" 
def read_bound(): 
    """Reads the upper bound from the standard input (keyboard). 
     If the user enters something that is not a positive integer 
     the function issues an error message and retries 
     repeatedly""" 

    while True: 
     try: 
      upper_bound = int(input("Enter the upper bound: ")) 
     except Exception: 
      print("You must enter a positive number.") 
     else: 
      return upper_bound 


def is_perfect_square(num): 
    """Return true if and only if num is a perfect square""" 
    for candidate in range(1, num): 
     if candidate * candidate == num: 
      return True 
    return False 



def print_squares(upper_bound, squares): 
    """Print a given list of all the squares up to a given upper bound""" 
    print("The perfect squares up to {} are: ". format(upper_bound)) 
    for square in squares: 
     print square, ' ' 


def main(): 
    """Calling the functions""" 
    upper_bound = read_bound() 
    squares = [] 
    for num in range(2, upper_bound + 1): 
     if is_perfect_square(num): 
      squares.append(num) 

    print_squares(upper_bound, squares) 

if __name__ == '__main__': 
    main()