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Python | Check if given string is numeric or not
  • Last Updated : 26 May, 2019

Given a string, write a Python program to check if the string is numeric or not.

Examples:

Input:  28
Output: digit

Input: a
Output: not a digit. 

Input: 21ab
Output: not a digit. 

 
Code #1: Using Python regex

re.search() : This method either returns None (if the pattern doesn’t match), or a re.MatchObject that contains information about the matching part of the string. This method stops after the first match, so this is best suited for testing a regular expression more than extracting data.




# Python program to identify the Digit
  
# import re module
  
# re module provides support
# for regular expressions
import re
  
# Make a regular expression
# for identifying a digit
regex = '^[0-9]+$'
      
# Define a function for
# identifying a Digit
def check(string): 
  
     # pass the regualar expression
     # and the string in search() method
    if(re.search(regex, string)): 
        print("Digit"
          
    else
        print("Not a Digit"
      
  
# Driver Code 
if __name__ == '__main__'
      
    # Enter the string 
    string = "28"
      
    # calling run function 
    check(string)
  
    string = "a"
    check(string)
  
    string = "21ab"
    check(string)
  
    string = "12ab12"
    check(string)


Output:



Digit
Not a Digit
Not a Digit
Not a Digit

 
Code #2: Using string.isnumeric() function




# Python code to check if string is numeric or not
      
# checking for numeric characters 
string = '123ayu456'
print(string.isnumeric()) 
     
string = '123456'
print(string.isnumeric()) 


Output:

False
True

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