Mastering String Manipulation in Python: A Beginner's Guide

Manipulating with strings

1. String Declaration: You can declare strings using either single quotes (‘) or double quotes (“).

s1 = ‘Hello’

s2 = “World”

2. Multi-line Strings: For strings that span multiple lines, use triple quotes (”’ or “””).

multiline_string = ”’This is

a multi-line

string”’

3. Accessing Characters: ( individual characters in a string using indexing)

s = “”

print(s[0]) 

print(s[-1])

4. String Slicing:(extract a substring from a string.)

s = “Hello, World!”

print(s[0:5])  # Output: Hello

print(s[7:])   # Output: World!

print(s[:5])   # Output: Hello

5. String Length🙁 by len() function)

s = “Hello”

print(len(s))  # Output: 5

6. String Methods: (built-in methods)

• • upper(): Converts a string to uppercase.

s = “hello”

print(s.upper())  # Output: HELLO

1. • lower(): Converts a string to lowercase.

s = “HELLO”

print(s.lower())  # Output: hello

1. • strip(): Removes leading and trailing whitespace.

s = ”  hello  “

print(s.strip())  # Output: hello

1. • replace(old, new): Replaces occurrences of a substring with another substring.

s = “Hello, World!”

print(s.replace(“World”, “”))  # Output: Hello, !

1. • split(): Splits a string into a list of substrings based on a delimiter.

s = “apple,banana,cherry”

print(s.split(“,”))  # Output: [‘apple’, ‘banana’, ‘cherry’]

1. • join(): .

fruits = [“apple”, “banana”, “cherry”]

print(“, “.join(fruits))  # Output: apple, banana, cherry

1. • find(sub):  returnsfirst occurrence of a substring. Returns -1 if not found.

s = “hello”

print(s.find(“e”))  # Output: 1

print(s.find(“z”))  # Output: -1

1. • count(sub):( no of occurrences of a substring)

s = “hello hello”

print(s.count(“hello”)) 

7. String Concatenation: (+ operator).

s1 = “Hello”

s2 = “World”

8. String Formatting:  provides several ways to format strings:

• • f-strings (formatted string literals): Introduced in  3.6, it allows you to embed expressions inside string literals.

name = “Alice”

age = 25

print(f”Name: {name}, Age: {age}”)

1. • format() method: Older method, but still commonly used.

name = “Bob”

print(“Hello, {}!”.format(name))  # Output: Hello, Bob!

1. • String interpolation using % (older style):

name = “Charlie”

print(“Hello, %s!” % name)  # Output: Hello, Charlie!

9. String Immutability: Since strings are immutable, attempting to change a character in a string will raise an error:

s = “Hello”

s[0] = “h”  //TypeError

s = “Hello”

s = “h” + s[1:]

print(s)  # Output: hello

Example:whether a string is palindrome or not.

s1=”aba”

s2=s1[::-1]

print(s1==s2)

if s1==s2:

    print(“palindrome”)

else:

    print(“not a palindrome”)

Program tofind out substring of string

s1=”I love india”

s2=”love”

if s2 in s1:

print(“equal”)

else:

print(“not equal”)

Find the  substring  of all the strings

s1 =”abcaaabba”

s1=s1.lower()

substring=[]

length=len(s1)

print(length)

for i in range(0,length):

    for j in range(i+1,length+1):

               substring.append(s1[i:j])

my_set = set(substring)

print(my_set)