Python Strings

A string is a character of sequence in any programming language. Python provides a powerful set of operations and functions over the string that makes python fun to program on strings.

How to create a string in Python?

Python strings are declared using a single quote or double quote or triple quote.

# Single Line Strings
name = "John Doe" # Double Quote
friend = 'Ricky Ponting' # Single Quote

# Multiline String separated by a black slash at the end of each line
hello = "Hello\
world"

# Using triple quotation marks
welcome = """welcome 
to Programming 
World of Python"""

How to access values of a string in Python?

We can use a slice operator [] and [:] to get a substring from a string in Python. The index of string starts from 0 and -1 represents the end of the string. The concatenation operation can be done using plus (+) sign and asterisk(*) serves as the repetition operator.

Let us explore some examples:-

str = 'Hello World!'
print str          # Prints complete string
print str[0]       # Prints first character of the string
print str[2:5]     # Prints characters starting from 3rd to 5th
print str[2:]      # Prints string starting from 3rd character
print str * 2      # Prints string two times
print str + "TEST" # Prints concatenated string

How to change or delete a string?

Python strings are immutable, meaning you cannot change once it has been created. One thing you can do is update the variable with another string. For example, the following operation is not permitted.

name = 'John'
name[0] = 'd'
print(name)

It results in an error as :-

name = 'John'
name = 'Alex'
print(name)

We cannot delete or remove characters from a string. But we can delete whole string using a del function.

What are the Python String Operations?

Python provides the various operator to work on Python string data type. Let’s have a look at the information provided in the table as below:-

What are escape characters in Python?

An escape character gets interpreted; in a single quoted as well as double-quoted strings. Here is the list of escape sequences:-

Examples for Escape characters in Python

print("This is \"double quote\" print")
print("C:\\Python32\\Lib")
print("This is printed\nin two lines")
print("This is \x48\x45\x58 representation")

Output:-

How to format strings in Python?

We can use % operator to format string. It gives the C like functionality in Python. Let’s jump right to an example:-

print("Hello, My name is %s and I live at %s" % ('John Doe', 'New York'))
# Output :- 
# Hello, My name is John Doe and I live at New York

Format symbols and their use is tabulated below:-

The format() Method for Formatting Strings

We can use a better version of the format method for formatting string.

Let us explore with some examples:-

# default arguments
print("Hello {}, your marks roll number is {}.".format("John", 79))

# positional arguments
print("Hello {0}, your roll number is {1}.".format("John", 79))

# keyword arguments
print("Hello {name}, your roll number is {roll}.".format(name="John", roll=79))

# mixed arguments
print("Hello {0}, your roll number is {roll}.".format("John", roll=79))

The output of the above program is:-

What are the built-in string methods to work with string in Python?

Python includes a ton of built-in methods to work with strings. We can call the method using string.method() and get the desired output.

Let us checkout some of these methods in action:-

test = "Python is fun to program"
print("john Doe".capitalize())
print("John Doe".upper())
print(test.split())
print("Length of test string is:", len(test))
print(test.replace('fun', 'awesome'))