如何在Python中排除输入变量的特定类型？

如何解决如何在Python中排除输入变量的特定类型？

我创建了一行斐波那契数字。首先需要输入数字来指定斐波那契数列的大小，实际上是行的大小。该数字必须是> = 2的整数。

结果是打印出所有斐波那契数，直到该行的最后一个数，并且它们各自的索引都在该行中！之后，需要取出该行的一个切片，结果是打印出该切片中的所有数字及其各自的索引。

我成功地掌握了排除不在指定范围内的所有值的方法，但是我没有成功排除数字和其他非期望类型的输入，例如，我想排除输入变量的浮点类型和字符串类型输入变量。

我指定了输入变量的不期望类型是float和string！但是它报告我一个错误！如何克服这个问题，或者换句话说，如何指定排除浮动变量和字符串变量以不向我报告错误的要求？

代码：

while True:
    n = int(input('Please enter the size of Fibonacci row - positive integer number(N>=2)!'))

    if n < 2:
        print('This is not valid number! Please enter valid number as specified above!')
        continue
    elif type(n)==float: # this line is not working!
        print('The number has to be an integer type,not float!')
        continue
    elif type(n)==str: # this line is not working!
        print(  'The number has to be an integer type,not string!')
        continue
    else:
        break

def __init__(self,first,last):
    self.first = first
    self.last = last

def __iter__(self):
    return self

def fibonacci_numbers(n):
    fibonacci_series =  [0,1]
    for i in range(2,n):
        next_element = fibonacci_series[i-1] + fibonacci_series[i-2]
        fibonacci_series.append(next_element)
    return fibonacci_series

while True:
    S = int(input('Enter starting number of your slice within Fibonacci row (N>=2):'))

    if S>n:
        print(f'Starting number can not be greater than {n}!')
        continue
    elif S<2:
        print('Starting number can not be less than 2!')
        continue
    elif type(S)==float: # this line is not working!
        print('The number can not be float type! It has to be an integer!')
        continue
    elif type(S)==str: # this line is not working!
        print('Starting number can not be string! It has to be positive integer number greater than or equal to 2!')
        continue
    else:
        break

while True:
    E = int(input(f'Enter ending number of your slice within Fibonacci row(E>=2) and (E>={S}):'))

    if E<S:
        print('Ending number can not be less than starting number!')
        continue
    elif E>n:
        print(f'Ending number can not be greater than {n}')
        continue
    elif E<2:
        print('Ending number can not be greater than 2!')
        continue
    elif type(E)==float: # this line is not working!
        print('Ending number can not be float type! It has to be an integer type!')
        continue
    elif type(E) ==str: # this line is not working!
        print(f'Ending number can not be string! It has to be positive integer number greater than or equal to {S}')
        continue
    else:
        break

print('Fibonacci numbers by index are following:')
for i,item in enumerate(fibonacci_numbers(n),start = 0):
    print(i,item)

fibonacci_numbers1 = list(fibonacci_numbers(n))
print('Fibonacci numbers that are within your slice with their respective indices are following:')
for i,item in enumerate(fibonacci_numbers1[S:E],start = S):
    print(i,item)

解决方法

第一行

    n = int(input('Please enter the size of Fibonacci row - positive integer number(N>=2)!'))

您要将输入转换为int，因此用户提供的任何内容都将转换为int。

如果您希望代码正常运行，请用此代码替换

n = input('Please enter the size of Fibonacci row - positive integer number(N>=2)!')

,

使用try/except/else测试输入。如果字符串值严格不是整数，则int()会引发ValueError。

>>> while True:
...   s = input('Enter an integer: ')
...   try:
...     n = int(s)
...   except ValueError:
...     print('invalid')
...   else:
...     break
...
Enter an integer: 12a
invalid
Enter an integer: 1.
invalid
Enter an integer: 1.5
invalid
Enter an integer: 1+2j
invalid
Enter an integer: 5
>>>

,

如果需要检查类型，通常使用isinstance更好，例如。 g。：

if isinstance(var,int) or isinstance(var,str):
    pass  # do something here

,

已解决：-)只需在我们的代码中添加 try 块，如下所示：

while True:
  try:
    num = int(input("Enter an integer number: "))
    break
  except ValueError:
      print("Invalid input. Please input integer only")  
      continue

print("num:",num)

投票并检查：-）