In Python, String is used for storing the URL(Uniform Resource Locator), file paths, JSON data, and virtually any textual information. Python strings are sequences of individual characters, which means we can access the specific characters of a string using indexing and slicing.
Syntax of Python String
str=” My Name is Python”
print(str)
What is a String in Python?
In the Python programming language, a string is a sequence of characters within either single quotes, double quotes, or triplet quotes. Strings can contain letters, numbers, symbols, and whitespace characters. Python strings are immutable, which means the content of the string cannot be changed once it is defined.
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Creating a Python String
In the Python programming language, we make the strings by enclosing them in single or double quotation marks. Python programming language also supports the triple quotes for defining the Python programming language.
Python String Example
str='Hello Python Programming language'
print(str)
str2 = "Hello Python 2"
print(str2)
str3 = “”" Hello Python 3"””
print(str3)
Python String Indexes
In the Python programming language, we also can access individual characters from the string using the indexes. Each character in a string has a unique index. It starts from 0 for the first character, 1 for the second character, and so on. In the Python programming language, we can also access the string using the negative indexes. We can access the end of the string, with -1 representing the last character, -2 representing the second to last character, and so far.
Python Program
str="Programming"
print("Positive Indexing")
print(str[0])
print(str[1])
print(str[2])
# negative indexing
print("Negative Indexing")
print(str[-1])
print(str[-2])
print(str[-3])
Output
Positive Indexing
P
r
o
Negative Indexing
g
n
I
Accessing Characters in Python String
In Python, we can access the string using indexing. Indexing allows negative and positive characters from the back of the string. For example, -1 refers to the last character of the string, -2 refers to the second-last character in the string, and so on.
Accessing the index out of the range will cause an IndexError in Python language.
Program
str = "herovired"
print(str[0])
Output
h
82.9%
of professionals don't believe their degree can help them get ahead at work.
Strings Indexing and Splitting
String Indexing: In Python, a string is a sequence of characters. Using Python’s indexing, we can get the individual character by the single character. The index starts from 0, the second index is 1, and so on.
The following program demonstrates the example
Program
str = "Hello"
print(str[0])
print(str[1])
print(str[2])
print(str[3])
print(str[4])
Output
H
e
l
l
o
Splitting: We can split the string using the split() function in Python. This method splits a string into a list using a specified delimiter. The following program demonstrates the string splits().
Program
string = "one, two, three"
words = string.split(',')
print(words)
Output
['one', 'two', 'three']
Reversing a Python String
In the Python programming language, we also reverse a string using the string slice method. In this example, we will reverse a string by accessing the index. In slicing, we will not specify the first two parts of the slice. That indicates that we are considering the whole string, from the last point to the last index.
The following program demonstrates the reverse of a string.
Program
#Program to reverse a string
str2 = "helloworld"
print(str2[::-1])
Output
dlrowolleh
Deleting Strings in Python
String are immutable characters. In the simple world. After assigning the string, we cannot make any changes to it. We cannot make any changes to it. We cannot remove or delete any character of the string. But in Python, we can delete the whole string using the del keyword.
The following program demonstrates the model keyword in Python
Program
str = "Helloworld"
print(str)
del str ;
print(str)
Output
Helloworld
<class 'str'>
Updating/Reassigning Strings in Python
Strings are immutable. It means, we cannot change the string after the declaration. But we can reassess the string in Python. Stings cannot be completed with a new string. Let’s see the following example of string reassigning.
Program
message="Welcome to the Programming world"
print(message)
message="Hacking World" #reassigning a new string
print(message)
Output
Welcome to the Programming world
Hacking World
Python Escape Sequence
A character with a backslash (\) just before it is called an escape sequence or escape character. We use escape characters to perform specific tasks while running your program. Escape Sequence is used when a programmer wants to add double quotes or single quotes in a program. There are many escape sequence characters available in the Python language.
List of Escape Sequences Available in Python
| Escape Sequence | Meaning |
| \’ | Single Quote |
| \\” | Double Quote |
| \\ | Backslash |
| \n | Newline |
| \r | Carriage Return |
| \t | Horizontal Tab |
| \b | Backspace |
| \f | Formfeed |
| \v | Vertical Tab |
| \0 | Null Character |
| \N{Name} | Unicode character named in database lookup |
| \uxxxxxxxx | Unicode character with a 16-bit hex value |
| \Uxxxxxxxx | A Unicode character with a 32-bit hex value |
| \000 | A character with octal value ooo |
| \xhh | The character with a hex value |
Also Read: Arrays in Python
Python String Formatting
In Python, we can format the string data type with the use format() method, which is a versatile function for formatting strings in Python. The format method contains curly braces {} as a placeholder, which can hold the arguments according to the position or keyword to specify the order.
Example: In this example, we will declare a string containing curly brackets and pass the dynamic string in these curly braces.
Program
# Python Program for
# Formatting of Strings
# Default order
String1 = "{} {} {}".format('Hello', 'Programming', 'World')
print("Print String in default order: ")
print(String1)
# Positional Formatting
String1 = "{1} {0} {2}".format('Hello ', 'Programming', 'World')
print("\nPrint String in Positional order: ")
print(String1)
# Keyword Formatting
String1 = "{l} {f} {g}".format(g='Hello', f='Computer', l='Programming')
print("\nPrint String in order of Keywords: ")
print(String1)
Output
Print String in default order:
Hello Programming World
Print String in Positional order:
Programming Hello World
Print String in order of Keywords:
Programming Computer Hello
Iterate a String using a loop
We can also iterate the string using the while loop and for loop in Python language. Python allows access to the single characters in the string one by one using any loop.
Using a for-loop: The following program demonstrates the for-loop example in Python
str = "hello world"
for c in str:
print(c)
Output
h
e
l
l
o
w
o
r
l
d
Using a while loop: The following program iterates a String using a while loop.
string = "Hello World"
index = 0
while index < len(string):
print(string[index])
index += 1
Output
H
e
l
l
o
W
o
r
l
d
Useful Python String Operations
Python language provides various operations to manipulate strings efficiently. Here I am discussing the common operations that are performed in strings.
- Logical Operators on String
- String Template Class
- Split a string
- String Slicing
- Find all duplicate characters in string
- String formatting using %
Python String Constants
| Built-in Function | Description |
| string.ascii_letter | Concatenation of the ascii_lowercaes and ascii_uppercae constants |
| string.ascii_lowercase | Concatenations of lowercase letters |
| string.ascii_uppercase | Concatenations of uppercase letters |
| string.digits | Digit in strings |
| string.letters | Concatenation of strings lowercase and uppercase |
| string.lowercase | A string must contain lowercase letters |
| string.octdigits | Octadigit in a string |
| string.punctuation | ASCII characters have punctuation characters. |
| string.printable | Strings of characters which are printable |
| Strig.endswith() | Return true if the string ends with a given suffix otherwise, this method returns false. |
| Strings.startswith() | This method returns true if a string starts with the given prefix otherwise. This method returns false. |
| String.isdigit() | This method returns true if all characters are digits otherwise. This method returns false. |
| String.isdecimal() | This method returns true if all characters are decimal |
| str.format() | This method allows substitution in an existing string |
| String.index | This method returns the position of the first occurrence of a substring in a string |
| replace() | This method returns the string where all strings are replaced with another string. |
| string.swapcase() | This method converts all uppercase characters to lowercase and vice versa of the given string. |
Compare Strings in Python
We can compare the string in Python using the comparison operators (==,!=,<,> <=, >=) compare strings.
The following program demonstrates the comparison of the strings.
Program
string1 = "apple"
string2 = "Apple"
print(string1 == string2)
print(string1 != string2)
print(string1 < string2)
print(string1 > string2)
print(string1 <= string2)
print(string1 >= string2)
Output
False
True
False
True
False
True
String Membership Test
The string member is nothing much. It is the test to check if a substring is present in a certain string.
To check if a substring is present in a string, we can use the “in” operator. The result of this statement would be a boolean value. It will return true if the substring is present in the string; otherwise, it will return false.
Program
print('str' in 'str is present or not str')
print('word' in 'Harry Potter')
Output
True
False
Unicode String
In Python language, normal strings are stored internally as 8-bit ASCII, while Unicode strings are stored in 16-bit Unicode. Unicode strings allow you to work with different language and character sets.
The following program demonstrates the Unicode String example.
Program
# Creating a Unicode string directly
unicode_str = "Hello, 世界!"
print(unicode_str)
Output
Hello, 世界!Multi-line Strings
We can also implement multi-line strings in the Python language. To do so, we use backlash, brackets, and triple quotes.
The following program demonstrates a multi string example in Python
Program
multiline_string = '''This is a
multiline
string.'''
print(multiline_string)
colors = ("multi-line string"
"red \n"
"blue \n"
"green \n"
"yellow \n"
)
print(colors)
x = "multiline String" \
"I love Python" \
"Python Language"
print(x)
Output
This is a
multiline
string.
multi-line string red
blue
green
yellow
Python String Methods
Python programming language offers a rich set of string methods that allow developers to manipulate and process text efficiently. These methods are essential for Python programmers. A string is a fundamental data type in the Python language. It is used in a wide range of applications. Below are some useful string methods, along with practical examples to demonstrate their usage.
- upper(): This string method is used to convert a string into Uppercase
- lower(): This string method is used to convert a string into lowercase
- split(): This method divides a string into a list of substrings based on a delimiter
- join(): This method joins the elements of an iterable into a single string, using the string as a delimiter.
- find(): This method finds the first occurrence of the specified string otherwise, it will return the -1 if the value is not found.
- count(): This method returns the number of characters that occur in the string
- replace(): This method replaces a specified string with another specified string.
Program
text = "Hello, World!"
print(text.upper()) # Output: HELLO, WORLD!
print(text.lower()) # Output: hello, world!
text = " Hello, World! "
print(text.strip()) # Output: Hello, World!
text = " Hello, World! "
print(text.strip()) # Output: Hello, World!
text = "Python is versatile and powerful"
words = text.split()
print(words) # Output: ['Python', 'is', 'versatile', 'and', 'powerful']
new_text = '-'.join(words)
print(new_text) # Output: Python-is-versatile-and-powerful
text = "Python is powerful, and Python is easy to learn."
print(text.find("Python")) # Output: 0
print(text.count("Python")) # Output: 2
text = "Python is easy to learn"
new_text = text.replace("easy", "fun")
print(new_text) # Output: Python is fun to learn
Output
HELLO, WORLD!
hello, world!
Hello, World!
Hello, World!
['Python', 'is', 'versatile', 'and', 'powerful']
Python-is-versatile-and-powerful
0
2
Python is fun to learn
List of String Methods in Python
Python has a rich set of string methods. Here is the list of in-built Python string methods.
| Methods | Descriptions |
| center() | This method aligns the string in the center |
| count() | This method counts the string characters |
| encode() | This method encodes the string, using the specified encoding. |
| endsWith() | This method returns true if the string ends with a specified value; otherwise returns false. |
| expandtabs() | This method sets the tab size to the specified number |
| find() | This method finds the first occurrence of the string if the string is not found, it will return -1 |
| strip() | This method removes any leading and trailing whitespaces. |
| format_map() | This method returns a dictionary value. |
| index() | This method finds the first occurrence of species value |
| isalnum() | This method returns true if the string is alphanumeric otherwise, It will return false. |
| isalpha() | This method returns true if all the characters are alphabet |
| isdecimal() | This method returns true if all the characters are decimal; otherwise, it will return false |
| isdigit() | This method returns true if all the characters are digits otherwise, it will return false. |
| isidentifier() | This method returns true if the string is a valid identifier otherwise, it returns false. |
| islower() | This method returns true if all the characters are lower otherwise, it will return false. |
| isnumeric() | This method returns true if all the characters are numeric otherwise, It will return false. |
| isprintable() | This method returns true if all the characters are printable otherwise, it will return false. |
| lower() | This method returns a string where all the characters are lower |
| lstrip() | This method removes any leading characters from the strip |
| maketrans() | This method returns a mapping table |
| partition() | This method searches the specified string in the string. |
| replace() | This method replaces a specified string with a specified string. |
| isprintable() | This method returns true if all the characters in the string are printable. If not, it returns false. |
| istitle() | This method returns true if all words are strings are titles otherwise returns false |
| rfind() | This method returns the highest index of the substring |
| splitlines() | This method splits the lines at line boundaries |
| zfill() | This method adds zeros(0) at the beginning of the string until it reaches the specified length of the string. |
| rpartition() | This method splits the string into three parts |
Also read: Pandas in Python
Conclusion
In this article, we learned about various types of string methods in the Python programming language. We learned about the reverse() method for reversing the string and the replace() method for replacing the specified string with a specific string. Python provides a rich set of built-in methods for string manipulations, allowing you to perform various operations efficiently. If you want to learn more about the Python programming language, you can check out the Accelerator Program in Business Analytics and Data Science.
What are Python string methods?
How do I convert the string into uppercase in Python?
How can I check if a string starts and ends with a specific substring?
How do I convert a string to a list of characters or vice versa?
How do I find the index of a substring within a string?
Updated on September 14, 2024