String Methods In
Python
Changing the
capitalization of a string
§ Python's string type provides
many functions that act on the capitalization of a string.
str.upper()
§ str.upper takes every
character in a string and converts it to its uppercase equivalent, for example:
word=input('enter
string in lowercase')
print('Original String is:- ',word)
print('capitalization of a string is:- ',word.upper())
Output:
enter string in lowercase python
Original String is: - python
capitalization of a string is: - PYTHON
str.lower()
§ str.lower does the
opposite; it takes every character in a string and converts it to its lowercase
equivalent:
word=input('enter string in UpperCase')
print('Original String is:- ',word)
print('capitalization of a string is:- ',word.lower())
Output:
enter string in UpperCase PYTHON
Original String is:- PYTHON
capitalization of a string is:-
python
str.capitalize()
§ str.capitalize returns a capitalized version of the
string, that is, it makes the first character have upper case and the rest
lower:
word=input('enter string ')
print('Original
String is:- ',word)
print('capitalization of a string
is:- ',word.capitalize())
Output:
enter string python
Original String is:- python
capitalization of a string is:-
Python
str.title()
§ str.title returns the title cased version of the
string, that is, every letter in the beginning of a word is made upper case and
all others are made lower case:
word=input('enter string ')
print('Original String is:- ',word)
print('Titlelization of a string is:- ',word.title())
Output
enter string india is my country
Original String is:- india
is my country
Titlelization of a string is:-
India Is My Country
str.swapcase()
§ str.swapcase returns a new string object in which
all lower case characters are swapped to upper case and all upper case
characters to lower:
word=input('enter string ')
print('Original String is:- ',word)
print('swapcase
of a string is:- ',word.swapcase())
Output
enter string india Is my cOUNtry
Original String is:- india
Is my cOUNtry
swapcase of a string is:-
INDIA iS MY CounTRY
Removing spaces from
the string:
|- Stripping unwanted
leading/trailing characters from a string
str.strip([chars])
§ str.strip acts on a given string and removes
(strips) any leading or trailing characters contained in the argument chars; if
chars is not supplied or is None, all white space characters are removed by
default. For example:
word=input('enter string ')
print('Original String is:- ',word)
print('After Removel leading and trailing space of a string
is:-',word.strip())
Output
enter string python is a prog lang
Original String is:-
python is a prog lang
After Removel leading and trailing space of a string is: - python
is a prog lang
§ If chars is supplied, all characters contained in it
are removed from the string, which is returned. For example:
word=input('enter
string ')
print('Original String is:- ',word)
print('After Removel leading and trailing space of a string
is:-',word.strip('$'))
Output
enter string $python is a prog lang
Original String is:- $python is a prog lang
After Removel leading and trailing space of a string is:- python
is a prog lang
str.rstrip([chars])
and str.lstrip([chars])
§ rstrip()===>To
remove spaces at right hand side
§ lstrip()===>To
remove spaces at left hand side 3
word=input('enter string ')
print('Original String is:- ',word)
print('After Removel leading space of a string is:-',word.rstrip())
print('After Removel trailing space of a string is:-',word.lstrip())
Output
enter string python is a prog lang
Original String is:-
python is a prog lang
After Removel leading space of a string is:- python is a prog lang
After Removel trailing space of a string is:- python is a prog
lang
Counting number of
times a substring appears in a string
§ One method is available for counting the number of
occurrences of a sub-string in another string, str.count.
str.count(substring)
str.count(substring,begin,end)
|- from begin index to end-1 index substring
s='python is a prog
lang and java is prog lang'
print(s.count('o')) # The OutPut will be 3
print(s.count('lang')) # The OutPut will be 2
print(s.count('java')) # The OutPut will be 1
print(s.count('lang',20,len(s))) # The OutPut will be 1Replace all occurrences of one substring with another substring
§ Python's str type also has a method for replacing
occurrences of one sub-string with another sub-string in a given string.
§ S.replace(oldstring,newstring)
s='python is prog lang'
print(s) # The Output will be python is prog lang
s=s.replace('python','java')
print(s)
# The output
will be java is prog langWrite a python program to count the total number of occurrences of a given character in a string without using any loop?
word=input('enter string ')
char=input('enter
letter for which')
count =len(word)-len(word.replace(char,''))
print('Number
of occurances of',char ,' in ',word,' =
',count)
Output
enter string python
again python again
enter letter for which a
Number of occurrences of a in
python again python again = 4
Split a string based
on a delimiter into a list of strings
str.split(sep=None,
maxsplit=-1)
§ We
can split the given string according to specified seperator by using split()
method.
§ str.split
takes a string and returns a list of substrings of the original string
l=s.split(seperator)
§ The
default seperator is space. The return type of split() method is List
word=input('enter string ')
word_list=word.split()
print('Original String is:- ',word)
print('Lis of Word:-',word_list)
Output
enter string india is my country
Original String is: - india is my country
Lis of Word: - ['india', 'is', 'my', 'country']
print( " ".split())#The Output will be []
list='java,python,angular,php,sql'.split(',')
print(list)
§ The default is to split on every occurrence of the delimiter,
however the maxsplit parameter limits the number of splitting’s that occur. The
default value of -1 means no limit:
str='python is a prog lang'
print(str.split('a',maxsplit=0))
print(str.split('a',maxsplit=1))
print(str.split('a',maxsplit=2))
print(str.split('a',maxsplit=-1))
Output
['python is a prog lang']
['python is ', ' prog lang']
['python is ', ' prog l', 'ng']
['python is ', ' prog l', 'ng']
Write a python program to
count the number of words in a string?
word=input('enter
string ')
word_list=word.split()
count=0
for w in
word_list:
print(w)
count+=1
print('Total Word:-',count)
enter string india
is my country
Output
india
is
my
country
Total Word:- 4
Finding Substrings is present in Given String:
§ there
are 4 method available in python to finding position of substring in given
string.
1. find()
2. rfind()
3. index()
4. rindex()
1. find() Method In Python:
s.find(substring)
§ This
method returns the index position of first occurrence of the given substring.
If the given substring is not available then it will return -1.
s='java
and python is very very easy a prog lang'
print(s.find('java'))#The
Output will be 0
print(s.find('python'))#The
Output will be 9
print(s.find('very'))#The
Output will be 19
Note: -
§ By
default, find () method can search total string. but if you want to search
with-in the boundaries then you have to require to specify the boundaries to
search.
s.find(substring,bEgin,end)
§ It
will always search from begin index to end-1 index
s='java and python is very very easy a prog lang'
print(s.find('java'))#The Output will be 0
print(s.find('python',10,20))#The
Output will be -1
print(s.find('very',24,30))#The Output will be 24
2. rfind() Method In Python:
s.rfind(substring)
§ This
method returns the index position of last matching of the given substring. If
the given substring is not available then it will return -1.
s='java and python is very very easy a prog lang'
print(s.rfind('java'))#The Output will be 0
print(s.rfind('python'))#The
Output will be 9
print(s.rfind('very'))#The Output will be 24
print(s.rfind('php'))#The Output will be -1
3. index() Method In Python:
s.index(substring)
§ This
method returns the index position of first occurrence of the given substring.
If the given substring is not available then we will get ValueError.
s='java
and python is very very easy a prog lang'
print(s.index('java'))#The
Output will be 0
print(s.index('python'))#The
Output will be 9
print(s.index('very'))#The
Output will be 19
print(s.index('php'))
ValueError: substring not
found
2. rindex() Method In Python:
s.rfind(substring)
§ This
method returns the index position of last matching of the given substring. If
the given substring is not available then it will return -1.
s='java and python is very very easy a prog lang'
print(s.rindex('java'))#The
Output will be 0
print(s.rindex('python'))#The
Output will be 9
print(s.rindex('very'))#The
Output will be 24
print(s.rindex('php'))
#The Output will be ValueError: substring not found
Write
a python program to find the following output
email=input('enter
email')
userName=''
server=''
domain=''
atpos=email.find('@')
dotpos=email.rfind('.')
if
atpos!=-1 and dotpos!=-1:
userName=email[0:atpos]
server=email[atpos+1:dotpos]
domain=email[dotpos+1:]
print('userName
:=',userName)
print('Server
:=',server)
print('Domain
:=',domain)
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