Python - String Methods



Python's built-in str class defines different methods. They help in manipulating strings. Since string is an immutable object, these methods return a copy of the original string, performing the respective processing on it. The string methods can be classified in following categories −

Case Conversion Methods

This category of built-in methods of Python's str class deal with the conversion of alphabet characters in the string object. Following methods fall in this category −

Sr.No. Method & Description

1

capitalize()

Capitalizes first letter of string

2

casefold()

Converts all uppercase letters in string to lowercase. Similar to lower(), but works on UNICODE characters alos

3

lower()

Converts all uppercase letters in string to lowercase.

4

swapcase()

Inverts case for all letters in string.

5

title()

Returns "titlecased" version of string, that is, all words begin with uppercase and the rest are lowercase.

6

upper()

Converts lowercase letters in string to uppercase.

Alignment Methods

Following methods in the str class control the alignment of characters within the string object.

Sr.No. Methods & Description

1

center(width, fillchar)

Returns a string padded with fillchar with the original string centered to a total of width columns.

2

ljust(width[, fillchar])

Returns a space-padded string with the original string left-justified to a total of width columns.

3

rjust(width,[, fillchar])

Returns a space-padded string with the original string right-justified to a total of width columns.

4

expandtabs(tabsize = 8)

Expands tabs in string to multiple spaces; defaults to 8 spaces per tab if tabsize not provided.

5

zfill (width)

Returns original string leftpadded with zeros to a total of width characters; intended for numbers, zfill() retains any sign given (less one zero).

Split and Join Methods

Python has the following methods to perform split and join operations −

Sr.No. Method & Description

1

lstrip()

Removes all leading whitespace in string.

2

rstrip()

Removes all trailing whitespace of string.

3

strip()

Performs both lstrip() and rstrip() on string

4

rsplit()

Splits the string from the end and returns a list of substrings

5

split()

Splits string according to delimiter (space if not provided) and returns list of substrings.

6

splitlines()

Splits string at NEWLINEs and returns a list of each line with NEWLINEs removed.

7

partition()

Splits the string in three string tuple at the first occurrence of separator

8

rpartition()

Splits the string in three string tuple at the ladt occurrence of separator

9

join()

Concatenates the string representations of elements in sequence into a string, with separator string.

10

removeprefix()

Returns a string after removing the prefix string

11

removesuffix()

Returns a string after removing the suffix string

Boolean String Methods

Following methods in str class return True or False.

Sr.No. Methods & Description

1

isalnum()

Returns true if string has at least 1 character and all characters are alphanumeric and false otherwise.

2

isalpha()

Returns true if string has at least 1 character and all characters are alphabetic and false otherwise.

3

isdigit()

Returns true if the string contains only digits and false otherwise.

4

islower()

Returns true if string has at least 1 cased character and all cased characters are in lowercase and false otherwise.

5

isnumeric()

Returns true if a unicode string contains only numeric characters and false otherwise.

6

isspace()

Returns true if string contains only whitespace characters and false otherwise.

7

istitle()

Returns true if string is properly "titlecased" and false otherwise.

8

isupper()

Returns true if string has at least one cased character and all cased characters are in uppercase and false otherwise.

9

isascii()

Returns True is all the characters in the string are from the ASCII character set

10

isdecimal()

Checks if all the characters are decimal characters

11

isidentifier()

Checks whether the string is a valid Python identifier

12

isprintable()

Checks whether all the characters in the string are printable

Find and Replace Methods

Following are the Find and Replace methods in Python −

Sr.No. Method & Description

1

count(sub, beg ,end)

Counts how many times sub occurs in string or in a substring of string if starting index beg and ending index end are given.

2

find(sub, beg, end)

Determine if sub occurs in string or in a substring of string if starting index beg and ending index end are given returns index if found and -1 otherwise.

3

index(sub, beg, end)

Same as find(), but raises an exception if str not found.

4

replace(old, new [, max])

Replaces all occurrences of old in string with new or at most max occurrences if max given.

5

rfind(sub, beg, end)

Same as find(), but search backwards in string.

6

rindex( sub, beg, end)

Same as index(), but search backwards in string.

7

startswith(sub, beg, end)

Determines if string or a substring of string (if starting index beg and ending index end are given) starts with substring sub; returns true if so and false otherwise.

8

endswith(suffix, beg, end)

Determines if string or a substring of string (if starting index beg and ending index end are given) ends with suffix; returns true if so and false otherwise.

Translation Methods

Following are the Translation methods of the string −

Sr.No. Method & Description

1

maketrans()

Returns a translation table to be used in translate function.

2

translate(table, deletechars="")

Translates string according to translation table str(256 chars), removing those in the del string.

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