What is Python String?

# defining strings in Python
# all of the following are equivalent
my_string = 'Hello'
print(my_string)

my_string = "Hello"
print(my_string)

my_string = '''Hello'''
print(my_string)

# triple quotes string can extend multiple lines
my_string = """Hello, welcome to
the world of Python"""
print(my_string)

We can access individual characters using indexing and a range of characters using slicing. Index starts from 0. Trying to access a character out of index range will raise an IndexError. The index must be an integer. We can't use floats or other types, this will result into TypeError.

Python allows negative indexing for its sequences.

The index of -1 refers to the last item, -2 to the second last item and so on. We can access a range of items in a string by using the slicing operator :(colon).

#Accessing string characters in Python
str = 'programiz'
print('str = ', str)

#first character
print('str[0] = ', str[0])

#last character
print('str[-1] = ', str[-1])

#slicing 2nd to 5th character
print('str[1:5] = ', str[1:5])

#slicing 6th to 2nd last character
print('str[5:-2] = ', str[5:-2])

Output :-

str = programiz
str[0] = p
str[-1] = z
str[1:5] = rogr
str[5:-2] = am

str = "HELLO"
print(str[0])
print(str[1])
print(str[2])
print(str[3])
print(str[4])
# It returns the IndexError because 6th index doesn't exist
print(str[6])

# Given String
str = "itechxpert" javatpoint
# Start Oth index to end
print(str[0:])
# Starts 1th index to 4th index
print(str[1:5])
# Starts 2nd index to 3rd index
print(str[2:4])
# Starts 0th to 2nd index
print(str[:3])
#Starts 4th to 6th index
print(str[4:7])

Output:


itechxpert
chxp
ec
ite
hxp

str = "HELLO"
print(str)
str = "hello"
print(str)


Output:


HELLO
hello

str1 = "JAVATPOINT"
del str1
print(str1)


Output:


NameError: name 'str1' is not defined

Operator Description
+ It is known as concatenation operator used to join the strings given either side of the operator.
* It is known as repetition operator. It concatenates the multiple copies of the same string.
[] It is known as slice operator. It is used to access the sub-strings of a particular string.
[:] It is known as range slice operator. It is used to access the characters from the specified range.
in It is known as membership operator. It returns if a particular sub-string is present in the specified string.
not in It is also a membership operator and does the exact reverse of in. It returns true if a particular substring is not present in the specified string.
r/R It is used to specify the raw string. Raw strings are used in the cases where we need to print the actual meaning of escape characters such as "C://python". To define any string as a raw string, the character r or R is followed by the string.
% It is used to perform string formatting. It makes use of the format specifiers used in C programming like %d or %f to map their values in python. We will discuss how formatting is done in python.

# Using Curly braces
print("{} and {} both are the best friend".format("Devansh","Abhishek"))

#Positional Argument
print("{1} and {0} best players ".format("Virat","Rohit"))

#Keyword Argument
print("{a},{b},{c}".format(a = "James", b = "Peter", c = "Ricky"))


Output:


Devansh and Abhishek both are the best friend
Rohit and Virat best players
James,Peter,Ricky

# Python String Operations
str1 = 'Hello'
str2 ='World!'

# using +
print('str1 + str2 = ', str1 + str2)

# using *
print('str1 * 3 =', str1 * 3)

# Iterating through a string
count = 0
for letter in 'Hello World':
if(letter == 'l'):
count += 1
print(count,'letters found')


Output :-

3 letters found

>>> 'a' in 'program'
True
>>> 'at' not in 'battle'
False

Python includes the following built-in methods to manipulate strings −

Sr.No. Methods with Description
1 capitalize()
Capitalizes first letter of string

2 center(width, fillchar)
Returns a space-padded string with the original string centered to a total of width columns.

3 count(str, beg= 0,end=len(string))
Counts how many times str occurs in string or in a substring of string if starting index beg and ending index end are given.

4 decode(encoding='UTF-8',errors='strict')
Decodes the string using the codec registered for encoding. encoding defaults to the default string encoding.

5 encode(encoding='UTF-8',errors='strict')
Returns encoded string version of string; on error, default is to raise a ValueError unless errors is given with 'ignore' or 'replace'.

6 endswith(suffix, beg=0, end=len(string))
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.

7 expandtabs(tabsize=8)
Expands tabs in string to multiple spaces; defaults to 8 spaces per tab if tabsize not provided.

8 find(str, beg=0 end=len(string))
Determine if str 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.

9 index(str, beg=0, end=len(string))
Same as find(), but raises an exception if str not found.

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

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

12 isdigit()
Returns true if string contains only digits and false otherwise.

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

14 isnumeric()
Returns true if a unicode string contains only numeric characters and false otherwise.

15 isspace()
Returns true if string contains only whitespace characters and false otherwise.

16 istitle()
Returns true if string is properly "titlecased" and false otherwise.

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

18 join(seq)
Merges (concatenates) the string representations of elements in sequence seq into a string, with separator string.

19 len(string)
Returns the length of the string

20 ljust(width[, fillchar])
Returns a space-padded string with the original string left-justified to a total of width columns.

21 lower()
Converts all uppercase letters in string to lowercase.

22 lstrip()
Removes all leading whitespace in string.

23 maketrans()
Returns a translation table to be used in translate function.

24 max(str)
Returns the max alphabetical character from the string str.

25 min(str)
Returns the min alphabetical character from the string str.

26 replace(old, new [, max])
Replaces all occurrences of old in string with new or at most max occurrences if max given.

27 rfind(str, beg=0,end=len(string))
Same as find(), but search backwards in string.

28 rindex( str, beg=0, end=len(string))
Same as index(), but search backwards in string.

29 rjust(width,[, fillchar])
Returns a space-padded string with the original string right-justified to a total of width columns.

30 rstrip()
Removes all trailing whitespace of string.

31 split(str="", num=string.count(str))
Splits string according to delimiter str (space if not provided) and returns list of substrings; split into at most num substrings if given.

32 splitlines( num=string.count('\n'))
Splits string at all (or num) NEWLINEs and returns a list of each line with NEWLINEs removed.

33 startswith(str, beg=0,end=len(string))
Determines if string or a substring of string (if starting index beg and ending index end are given) starts with substring str; returns true if so and false otherwise.

34 strip([chars])
Performs both lstrip() and rstrip() on string.

35 swapcase()
Inverts case for all letters in string.

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

37 translate(table, deletechars="")
Translates string according to translation table str(256 chars), removing those in the del string.

38 upper()
Converts lowercase letters in string to uppercase.

39 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).

40 isdecimal()
Returns true if a unicode string contains only decimal characters and false otherwise.