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Python String isidentifier() Method

Last Updated : 09 Sep, 2022
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Python String isidentifier() method is used to check whether a string is a valid identifier or not. The method returns True if the string is a valid identifier, else returns False.

Python String isidentifier() method Syntax

Syntax:  string.isidentifier()

Parameters: The method does not take any parameters

Return Value:  The method can return one of the two values: 

  • True: When the string is a valid identifier.
  • False: When the string is not a valid identifier.

Python String isidentifier() Method Example

Python3




string = "Coding_101"
print(string.isidentifier())
 






                        










Output:


True


Note: A string is considered as a valid identifier if:


    

  • It only consists of alphanumeric characters and underscore (_)
    • 

  • Doesn’t start with a space or a number
    • 



Example 1: How isidentifier() works


Here, we have added some basic examples of using isidentifier() Method in Python




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















# String with spaces


string = "Geeks for Geeks"


print(string.isidentifier())


 


# A Perfect identifier


string = "GeeksforGeeks"


print(string.isidentifier())


 


# Empty string


string = ""


print(string.isidentifier())


 


# Alphanumerical string


string = "Geeks0for0Geeks"


print(string.isidentifier())


 


# Beginning with an integer


string = "54Geeks0for0Geeks"


print(string.isidentifier())



















                        







                        










Output: 


False
True
False
True
False


Example 2: Using Python String isidentifier() Method in condition checking


Since, Python String isidentifier() returns boolean we can directly use isidentifier() inside if-condition to check if a String is an indicator or not.




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















string = "geeks101"


if string.isidentifier():


    print(string, "is an identifier.")


else:


    print(string, "is not an identifier.")


 


string = "GeeksForGeeks"


if string.isidentifier():


    print(string, "is an identifier.")


else:


    print(string, "is not an identifier.")


 


string = "admin#1234"


if string.isidentifier():


    print(string, "is an identifier.")


else:


    print(string, "is not an identifier.")


 


string = "user@12345"


if string.isidentifier():


    print(string, "is an identifier.")


else:


    print(string, "is not an identifier.")



















                        







                        










Output:


geeks101 is an identifier.
GeeksForGeeks is an identifier.
admin#1234 is not an identifier.
user@12345 is not an identifier.




                                    


                                                                        

                                        

                                            

                                                

                                                    
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                                                    Chinmoy Lenka                                                

                                            

                                            

            
                                        

                                        

                                            
    

        
        
    
                                            

                                                
                                                
                                            

                                            

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