Python – Test if Kth character is digit in String

Given a String, check if Kth index is a digit.

Input : test_str = ‘geeks9geeks’, K = 5 
Output : True 
Explanation : 5th idx element is 9, a digit, hence True.
Input : test_str = ‘geeks9geeks’, K = 4 
Output : False 
Explanation : 4th idx element is s, not a digit, hence False. 

Method #1: Using in operator

In this, we create a string of numerics and then use in operator to check if Kth digit lies in that numeric string.

Python3

# Python3 code to demonstrate working of
# Test if Kth character is digit in String
# Using in operator

# initializing string
test_str = 'geeks4geeks'

# printing original String
print("The original string is : " + str(test_str))

# initializing K
K = 5

# checking if Kth digit is string
# getting numeric str
num_str = "0123456789"
res = test_str[K] in num_str

# printing result
print("Is Kth element String : " + str(res))

Output

The original string is : geeks4geeks
Is Kth element String : True

Method #2 : Using isdigit()

In this, we use inbuilt Py. function to solve this problem, and check if Kth element is digit.

Python3

# Python3 code to demonstrate working of
# Test if Kth character is digit in String
# Using isdigit()

# initializing string
test_str = 'geeks4geeks'

# printing original String
print("The original string is : " + str(test_str))

# initializing K
K = 5

# isdigit checks for digit
res = test_str[K].isdigit()

# printing result
print("Is Kth element String : " + str(res))

Output

The original string is : geeks4geeks
Is Kth element String : True

The Time and Space Complexity for all the methods are the same:

Time Complexity: O(1)

Auxiliary Space: O(1)

Method #3 : Using ord() method

Python3

# Python3 code to demonstrate working of
# Test if Kth character is digit in String

# initializing string
test_str = 'geeks4geeks'

# printing original String
print("The original string is : " + str(test_str))

# initializing K
K = 5
res=False
if(ord(test_str[K])>=48 and ord(test_str[K])<=57):
    res=True

# printing result
print("Is Kth element String : " + str(res))

Output

The original string is : geeks4geeks
Is Kth element String : True