Programming with Python

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String Functions and Methods

Table of Contents show

capitalize

  • The function capitalize( ) returns a string with first letter capitalized.
  • capitalize( ) function does not take any parameter
  • If the first letter of the string is an  upper case letter or a non-alphabetic character, it returns the original string

Syntax

string.capitalize( )

Example

str1 = "hello all"
print(str1.capitalize())

Output

Hello all

center

  • The center( ) method returns a string padded with specified fillchar
  • It does not modify the original string and default filler is a space

Syntax

string.center(width,[fillchar])
width – length of the string with padded characters fillchar (optional) – padding character

Example

str1 = "hello all"
str1.center(20,'*')

Output

'*****hello all******'

casefold

The casefold( ) method removes all case distinctions present in a string

Syntax

string.casefold( )

Example

a = "Hello All"
a.casefold( )

Output

'hello all'

count

The count( ) method returns the number of occurences of substring in the range [start, end]

Syntax

string.count(substring, start, end)
substring – string whose count is to be found start (optional) – starting index within the string where search starts end(optional) – ending index within the string where search ends

Example

str = "This is book"
substr = "i"
str.count(substr)
str.count(substr,3)
substr = "o"
str.count(substr,0,4)

Output

2
1
0

endswith

 The endswith( ) method returns True if a string ends with the specified suffix otherwise return false

Syntax

string.endwith(suffix, start,end)
suffix – string to be checked start(optional) – beginning position where suffix is to be checked within the string end(optional) – Ending position where suffix is to be checked within the string else returns a Boolean

Example

Text = "Python is very easy to learn"
result = Text.endswith('to learn')
print("check for to learn:",result)
result = Text.endswith('n')
print("check for n:",result)
result = Text.endswith('easy',6,13)
print("check for easy at start = 6 and end = 13:",result)
result=Text.endswith('easy',15,19)
print("check for easy at start = 15 and end = 19:",result)

Output

check for to learn: True
check for n: True
check for easy at start = 6 and end = 13: False
check for easy at start = 15 and end = 19: True

startswith

 The startswith( ) method returns true if a string starts with the specified prefix else it returns false

Syntax

string.startswith(prefix, start,end)
prefix – string or tuple of strings to be checked start – Beginning position where prefix is to be checked within the string end – Ending position where prefix is to be checked within the string

Example

Text = "Python is very easy to learn"
result = Text.startswith('to learn')
print("check for to learn:",result)
result = Text.startswith('python')
print("check for python:",result)

Output

check for to learn: False
check for python: False

upper

 The upper( ) converts all uppercase characters in a string into lowercase characters.

Syntax

string.upper( )

Example

str ="python is easy to learn"
print(str.upper())

Output

PYTHON IS EASY TO LEARN

lower

 The lower( ) converts all lowercase characters in a string into uppercase characters

Syntax

string.lower( )

Example

str ="PYTHON IS EASY TO LEARN"
print(str.lower())

title

The title( ) method converts the string to title case i.e. first characters of all the words are capitalized

Syntax

string.title( )

Example

str = "hello all"
print(str.title( ))

Output

Hello All

swapcase

The swapcase( ) method convers the lower case to upper case and vice versa

Syntax

string.swapcase( )

Example

str = "Hello All"
print(str.swapcase())

Output

hELLO aLL

split

The split( ) method breaks up a string at the specified separator and returns a list of string

Syntax

string.split( [separator],[maxsplit])
separator (optional) – Delimiter. string splits as the specified separator. If the separator is not specified, any whitespace (space, newline) string is a separator Maxsplit – the maxsplit defines the maximum number of splits.

Example

str = "python is easy to learn"
str1 = "python,easy,learn"
print(str.split())
print(str1.split(','))

Output

['python', 'is', 'easy', 'to', 'learn']
['python', 'easy', 'learn']

replace

  • The replace( ) method search for specified string and replaces it with new string value.
  • If the old string is not found, it returns the copy of the original string

Syntax

string.replace( old,new)

Example

person = "very, very intelligent"
print(person.replace("very","good"))

Output

good, good intelligent

join

The join( ) method returns a string concatenated with the elements of an iterable

Syntax

string.join(iterable)

Example

str1 = "Python"
a="*"
string1 = "abc"
string2 = "521"
print(a.join(str1))
print(string1.join(string2))

Output

P*y*t*h*o*n
5abc2abc1

isupper

The isupper( ) method returns true if all the characters in the given string is in upper case else it returns false

Syntax

string.isupper( )

Example

str1 = "Python"
str2 = "PYTHON"
print("Python:",str1.isupper())
print("PYTHON:",str2.isupper())

Output

Python: False
PYTHON: True

islower

The islower( ) method returns true if all the characters in the given string is in lower case else it returns false

Syntax

string.islower( )

Example

str1 = "Python"
str2 = "python"
print("Python:",str1.islower())
print("PYTHON:",str2.islower())

Output

Python: False
PYTHON: True

isalpha

The isalpha( ) returns True if all the characters in the string are alphabets otherwise it returns False

Syntax

string.isalpha( )

Example

str1 = "Python"
str2 = "GE8151python"
str3 = "Python is easy"
print("Python:",str1.isalpha())
print("PYTHON:",str2.isalpha())
print("Python is easy:",str3.isalpha())

Output

Python: True
PYTHON: False
Python is easy: False

isalnum

The isalnum( ) method returns True if all the characters in the string are alphanumeric, otherwise it returns false

Syntax

string.isalnum( )

Example

str1 = "Python"
str2 = "GE8151python"
str3 = "Python is easy"
print("Python:",str1.isalnum())
print("PYTHON:",str2.isalnum())
print("Python is easy:",str3.isalnum())

Output

Python: True
PYTHON: True
Python is easy: False

isdigit

The isdigit( ) method returns true if all characters in a string are digits, otherwise it returns false

Syntax

string.isdigit( )

Example

str1 = "Python"
str2 = "8151"
print("Python:",str1.isdigit())
print("8151:",str2.isdigit())

Output

Python: False
8151: True

isspace

The isspace( ) method checks whether the string consists of white space only

Syntax

string.isspace( )

Example

str1 = "Python"
str2 = "GE8151python"
str3 = "Python is easy"
str4 = "  "
print("Python:",str1.isspace())
print("PYTHON:",str2.isspace())
print("Python is easy:",str3.isspace())
print("   :",str4.isspace())

Output

Python: False
PYTHON: False
Python is easy: False
   : True

istitle

The istitle( ) method returns True if the string is a titlecased string, otherwise returns False

Syntax

string.istitle( )

Example

str1 = "Python"
str2 = "GE8151 python"
str3 = "Python Is Easy"
print("Python:",str1.istitle())
print("GE8151 python:",str2.istitle())
print("Python Is Easy:",str3.istitle())

Output

Python: True
GE8151 python: False
Python Is Easy: True

find

The find( ) method returns index of substring, if it is found. Otherwise -1 is returned

Syntax

string.find( )

Example

str1 = "Python is easy"
print("is:",str1.find("is"))
print("fun:",str1.find("fun"))

Output

is: 7
fun: -1

len

The len( ) method returns the length of the string

Syntax

len(string)

Example

str1 = "python"
print("Length of python:",len(str1))

Output

Length of python: 6

min

The min( ) method returns the minimum character in the string

Syntax

min(string)

Example

str1 = "python"
print("Minimum character of python:",min(str1))

Output

Minimum character of python: h

max

The max( ) method returns the maximum character in the string

Syntax

max(string)

Example

str1 = "python"
print("Maximum character of python:",max(str1))

Output

Maximum character of python: y

String Module

  • A module is a file containing python definitions, functions, statements
  • Standard library of python is extended as modules
  • To use these modules in a program, programmer needs to import the module
  • Once the module is imported, the functions or variables are referenced in the code
  • There is large number of standard modules also available in python
  • Standard modules are imported in the same way as user defined modules are imported

Syntax

import module_name

Example,

import string
print(string.punctuation)
print(string.digits)
print(string.printable)
print(string.capwords("Learn Python"))
print(string.hexdigits)
print(string.octdigits)

Output

!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
0123456789
123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
Learn Python
0123456789abcdefABCDEF
01234567

Escape sequences in strings

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