Скачать или смотреть String Functions in Python-Find, Index, Isalpha, Isdigit & Isalnum Functions in Python|Tutorial

find(): This is a built-in function in Python that returns the lowest index of the substring (if found). If not found, it returns -1. It is used with strings.

str = "Pycent, World!"
print(str.find("World")) # Output: 8
print(str.find("Universe")) # Output: -1


index(): This is another built-in function in Python that also returns the index of a substring. The difference between find() and index() is that index() raises an exception if the substring is not found.


str = "Pycent, World!"
print(str.index("World")) # Output: 8
try:
print(str.index("Universe")) # Raises ValueError
except ValueError:
print("Substring not found.")


isalpha(): This method returns True if all the characters in the string are alphabets (either lower case or upper case), otherwise, it returns False.

str = "Pycentworld"
print(str.isalpha()) # Output: True

str = "Pycent.com3"
print(str.isalpha()) # Output: False


isdigit(): This method returns True if all the characters in the string are digits, otherwise, it returns False.

str = "123456"
print(str.isdigit()) # Output: True

str = "123abc"
print(str.isdigit()) # Output: False


isalnum(): This method returns True if all the characters in the string are alphanumeric (either alphabets or digits), otherwise, it returns False.

str = "abc123"
print(str.isalnum()) # Output: True

str = "abc 123"
print(str.isalnum()) # Output: False

Notes prepared by: Pycent.com