String isidentifier() Method in Python

Python String isidentifier() Method

The isidentifier() method in Python is used to check whether a string is a valid identifier. An identifier is a name used to identify a variable, function, class, module, or any other object in Python. It must follow certain rules:

1. It can only contain letters (both uppercase and lowercase), digits (0-9), and underscores (_).
2. It must start with a letter (either uppercase or lowercase) or an underscore (_).

The isidentifier() method returns True if the string is a valid identifier according to these rules; otherwise, it returns False.

Here's the syntax of the isidentifier() method:

string.isidentifier()

Example:

# Examples of isidentifier() method
string1 = "variable_name"
string2 = "123abc"
string3 = "class"
string4 = "my-module"
string5 = "for"

result1 = string1.isidentifier()
result2 = string2.isidentifier()
result3 = string3.isidentifier()
result4 = string4.isidentifier()
result5 = string5.isidentifier()

print("String 1:", string1)
print("String 2:", string2)
print("String 3:", string3)
print("String 4:", string4)
print("String 5:", string5)

print("isidentifier() result for String 1:", result1)
print("isidentifier() result for String 2:", result2)
print("isidentifier() result for String 3:", result3)
print("isidentifier() result for String 4:", result4)
print("isidentifier() result for String 5:", result5)

Output:

String 1: variable_name
String 2: 123abc
String 3: class
String 4: my-module
String 5: for
isidentifier() result for String 1: True
isidentifier() result for String 2: False
isidentifier() result for String 3: True
isidentifier() result for String 4: False
isidentifier() result for String 5: False

In this example, string1 and string3 are valid identifiers, so isidentifier() returns True. string2, string4, and string5 are not valid identifiers according to Python's rules, so isidentifier() returns False.

The isidentifier() method is useful when you want to check if a given string can be used as an identifier for variables, functions, or other Python objects. It is commonly used for input validation when handling dynamically generated names in Python programs.