Python Strings

In Python, a string is a sequence of characters. For example, “hello” is a string containing a sequence of characters ‘h’, ‘e’, ‘l’, ‘l’, and ‘o’.

We use single quotes or double quotes to represent a string in Python. For example,

Here, we have created a string variable named string1. The variable is initialized with the string “Python Programming”.

Example: Python String:-

Output:-

In the above example, we have created string-type variables: name and message with values “Python” and “I love Python” respectively.

Here, we have used double quotes to represent strings, but we can use single quotes too.

Access String Characters in Python

We can access the characters in a string in three ways.

• Indexing: One way is to treat strings as a list and use index values. For example,

• Negative Indexing: Similar to a list, Python allows negative indexing for its strings. For example,

• Slicing: Access a range of characters in a string by using the slicing operator colon :. For example,

Note: If we try to access an index out of the range or use numbers other than an integer, we will get errors.

Python Strings are Immutable

In Python, strings are immutable. That means the characters of a string cannot be changed. For example,

Output:-

However, we can assign the variable name to a new string. For example,

Python Multiline String

We can also create a multiline string in Python. For this, we use triple double quotes “”” or triple single quotes ”’. For example,

Output:-

In the above example, anything inside the enclosing triple quotes is one multiline string.

Python String Operations

Many operations can be performed with strings, which makes it one of the most used data types in Python.

1. Compare Two Strings

We use the == operator to compare two strings. If two strings are equal, the operator returns True. Otherwise, it returns False. For example,

Output:-

In the above example,

1. str1and str2 are not equal. Hence, the result is False.
2. str1and str3 are equal. Hence, the result is True.

2. Join Two or More Strings

In Python, we can join (concatenate) two or more strings using the + operator.

In the above example, we have used the + operator to join two strings: greet and name.

Iterate Through a Python String

We can iterate through a string using a for loop. For example,

Output:-

Python String Length

In Python, we use the len() method to find the length of a string. For example,

String Membership Test

We can test if a substring exists within a string or not, using the keyword in.

Methods of Python String

Besides those mentioned above, there are various string methods present in Python. Here are some of those methods:

upper()	Converts the string to uppercase
lower()	Converts the string to lowercase
partition()	Returns a tuple
replace()	Replaces substring inside
find()	Returns the index of the first occurrence of substring
rstrip()	Removes trailing characters
split()	Splits string from left
startswith()	Checks if string starts with the specified string
isnumeric()	Checks numeric characters
index()	Returns index of substring

Escape Sequences in Python

The escape sequence is used to escape some of the characters present inside a string.

Suppose we need to include both a double quote and a single quote inside a string,

Since strings are represented by single or double quotes, the compiler will treat “He said, ” as a string. Hence, the above code will cause an error.

To solve this issue, we use the escape character \ in Python.

Here is a list of all the escape sequences supported by Python.

Escape Sequence	Description
\\	Backslash
\’	Single quote
\”	Double quote
\a	ASCII Bell
\b	ASCII Backspace
\f	ASCII Formfeed
\n	ASCII Linefeed
\r	ASCII Carriage Return
\t	ASCII Horizontal Tab
\v	ASCII Vertical Tab
\ooo	Character with octal value ooo
\xHH	Character with hexadecimal value HH

Python String Formatting (f-Strings)

Python f-Strings makes it easy to print values and variables. For example,

Output:-

Here, f'{name} is from {country}’ is an f-string.

This new formatting syntax is powerful and easy to use. From now on, we will use f-Strings to print strings and variables.

Boolean= Python bool()

The bool() method takes a specified argument and returns its boolean value.

Example-

bool() Syntax

The syntax of bool() is:

bool() Parameter

The bool() method takes in a single parameter:

• argument – whose boolean value is returned

bool() Return Value

The bool() method returns:

           False – if argument is empty, False, 0 or None

           True – if argument is any number (besides 0), True or a string

Example 1: Python bool() with True Arguments

Output:-

In the above example, we have used the bool() method with various arguments like integer, floating point numbers, and string.

Here, the method returns True values for arguments like 25, 25.14, ‘Python is a String’, and True

Example 2: bool() with False Arguments

Output:-

In the above example, the bool() method returns False values for arguments like 0, None, False and [].