Python String isidentifier() Method

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.