如何将输入字符限制为字母

Question

我不太了解python，我现在正在学习逆向工程，为了一个培训程序crackme.exe，我在python上找到了这个代码。请告诉我如何检查数字输入字符-只需要字母，数字必须排除或输出"输入error"

def keygen(name):   
word = 0          
for letter in name:   
word += ord(letter)

return word ^ 0x5678 ^ 0x1234 

import sys   
if __name__ == '__main__':   
if len(sys.argv) < 2:   
print("Name")
sys.exit(1)
else:
print(keygen(sys.argv[1].upper()))  

sys.argv
sys.exit(1)

Answer 1

您可以遍历输入字符串的每个字符并检查是否为字母表中的字母。

我在下面创建了一个名为is_valid的函数，它应该可以解决您的问题。如果您想更改哪些字符是有效的，您可以通过编辑alphabet变量来实现。

alphabet = "abcdefghijklmnopqrstuvwxyz"
def is_valid(text):
for char in text:
# char.lower() makes sure the text is lowercase, otherwise "Hello" would not be valid because capital H wasn't in the alphabet.
if char.lower() not in alphabet:
return False
else: # We've finished iterating, which means all characters were in the alphabet.
return True
if __name__ == '__main__':   
if len(sys.argv) < 2:   
print("Name")
sys.exit(1)
else:
if is_valid(sys.argv[1]): # Yay! Its valid so we can run our function
print(keygen(sys.argv[1].upper()))
else:
sys.exit(1) # Its not valid so we should exit with Code 1