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Validate string

I am trying to solve the following problem:

Given a string str, the task is to check if the string is a valid identifier or not. In order to qualify as a valid identifier, the string must satisfy the following conditions:

It must start with either underscore(_) or any of the characters from the ranges [‘a’, ‘z’] and [‘A’, ‘Z’]. There must not be any white space in the string. And, all the subsequent characters after the first character must not consist of any special characters like ,ドル #, % etc.

Examples:

Input: str= "_code123"

Output: Valid

Input: str = "123code_"

Output: Invalid

My attempted solution, which works:

def isValid(str1, n):
 # If first character is invalid
 if (((ord(str1[0]) >= ord('a') and
 ord(str1[0]) <= ord('z')) or
 (ord(str1[0]) >= ord('A') and
 ord(str1[0]) <= ord('Z')) or
 ord(str1[0]) == ord('_')) == False):
 return False
 # Traverse the string for the rest of the characters
 for i in range(1, len(str1)):
 if (((ord(str1[i]) >= ord('a') and
 ord(str1[i]) <= ord('z')) or
 (ord(str1[i]) >= ord('A') and
 ord(str1[i]) <= ord('Z')) or
 (ord(str1[i]) >= ord('0') and
 ord(str1[i]) <= ord('9')) or
 ord(str1[i]) == ord('_')) == False):
 return False
 # is a valid identifier
 return True
# Driver code
str1 = "_code123"
n = len(str1)
if (isValid(str1, n)):
 print("Valid")
else:
 print("Invalid")

How can I make the above code follow OOP principles, without so many nested ifs?

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Thank you! Can you please provide a bit of an explanation regarding what each of the reg ex expressions do? :)

nerdyGuy
– nerdyGuy

2021年04月25日 23:53:30 +00:00
Commented Apr 25, 2021 at 23:53
Go to the site and put my expression the site will explain automatically

DevScheffer
– DevScheffer

2021年04月25日 23:55:43 +00:00
Commented Apr 25, 2021 at 23:55

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Validate string

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