Python如何检查输入是字母还是字符 [英] Python how to check if input is a letter or character

问题描述

如何检查Python中输入的是字母还是字符？

How can I check if input is a letter or character in Python?

输入内容应为用户要检查的数字。
然后程序应检查用户提供的输入是否属于tribonacci序列（任务中给出了0,1,2），并且如果用户输入的内容不同于整数，则程序应继续运行。

Input should be amount of numbers user wants to check. Then program should check if input given by user belongs to tribonacci sequence (0,1,2 are given in task) and in case user enter something different than integer, program should continue to run.

n = int(input("How many numbers do you want to check:"))
x = 0

def tribonnaci(n):
    sequence = (0, 1, 2, 3)
    a, b, c, d = sequence
    while n > d:
        d = a + b + c
        a = b
        b = c
        c = d
    return d

while x < n:
    num = input("Number to check:")
    if num == "":
        print("FAIL. Give number:")
    elif int(num) <= -1:
        print(num+"\tFAIL. Number is minus")
    elif int(num) == 0:
        print(num+"\tYES")
    elif int(num) == 1:
        print(num+"\tYES")
    elif int(num) == 2:
        print(num+"\tYES")
    else:
        if tribonnaci(int(num)) == int(num):
            print(num+"\tYES")
        else:
            print(num+"\tNO")
    x = x + 1

推荐答案

您可以使用 num.isnumeric（）函数，如果输入为数字，则返回 True，如果输入非数字，则返回 False。

You can use num.isnumeric() function that will return You "True" if input is number and "False" if input is not number.

>>> x = raw_input()
12345
>>> x.isdigit()
True

您也可以使用try / catch：

You can also use try/catch:

try:
   val = int(num)
except ValueError:
   print("Not an int!")

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