Built in String Functions3 min read

Python treats strings as an object.It offers various methods that can be used to get our work done in no(or less) time.
There are several built-in functions available that allows us to modify and (or) manipulate data easily and efficiently.

Python offers a function dir which lists all the available methods in the particular object.

# This lists all methods available in class 'str'
>>>dir(str)
['__add__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'capitalize', 'casefold', 'center', 'count', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 'isalnum', 'isalpha', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

As there are many methods available we will discuss only a few important.

Some Important String Methods

1. len()

This method returns the length of the String.
Syntax:-
len(string)

2.capitalize()

This function creates the exact copy of string with the first letter in upper case.
Syntax:-
string.capitalize()

3.replace()

This function replaces all the occurences of old string with the new string.It takes two parameters.
Syntax:-
string.replace(old_string,new_string)

4.split()

This method breaks up a string by a specific separator and returns a list of sub-strings.It takes two parameters.
Syntax:-
string.split(separator,maxsplit)
Here both the parameters are optional.
Separator is used to give the sub-string which is to be used as delimiter. If separator is not specified,any white space,newline etc. is treated as separator.
Maxsplit defines the maximum no. of splits.By default,maxsplit is -1(which means no limit.)

>>>word="Hello!"
>>>print(len(word))
6
>>>string='This is Ram\'s book.'# Here \' is treated as a single character.
19
>>>s1="python"
>>>print(s1.capitalize())
Python
>>>print(string.replace(' is ',' was '))
#Here note that extra space is used so that the function don't change 'This' in 'Thwas'
This was Ram's book.
>>>item='Tea:Coffee:Oil:Shampoo'
>>>print(item.split(':',2))
['Tea','Coffee','Oil:Shampoo']
>>>print(item.split(sep=':',1))
['Tea','Coffee:Oil:Shampoo']
Important
  • String methods does not modify the original string.Rather they make a fresh copy of it.
  • We can use sep=”separator” in split function to define the separator when the maxsplit need not to be defined.
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