String in Python

What is a String?

A string is a sequence of characters enclosed in:

• Single quotes ' '
• Double quotes " "
• Triple quotes ''' ''' or """ """

Example

name = "Ankit"
city = 'Dhampur'
message = """Welcome to Python"""

Features of Strings

• Strings are immutable
• (cannot be changed after creation)

text = "Python"
# text[0] = 'J'   ❌ Error

• Strings are indexed.

word = "Python"

print(word[0])   # P
print(word[3])   # h

3. String Indexing

• Positive Indexing

As we have seen that list items have an index, we can access items using these indexes

text = "PYTHON"

P   Y   T   H   O   N
0   1   2   3   4   5

• Negative Indexing

Similar to positive indexing, negative indexing is also used to access items, but from the end of the list.

P   Y   T   H   O   N
-6 -5  -4  -3  -2  -1

Example-

text = "Python"

print(text[-1])   # n
print(text[-3])   # h

4. String Slicing

• In Python, slicing is a powerful tool that allows you to manipulate and extract data from sequences such as strings

Syntax

string[start : stop : step]

Example

text = "PYTHON"

print(text[1:4])   # YTH
print(text[:3])    # PYT
print(text[2:])    # THON
print(text[::2])   # PTO

5. String Operators

Example

print("Hello" + " World")
print("Hi " * 3)
print('P' in "PYTHON")

6. Common String Functions

1. len()

Returns length of string.

text = "Python"

print(len(text))

2. lower()

Converts string to lowercase.

text = "PYTHON"

print(text.lower())

3. upper()

Converts string to uppercase.

text = "python"

print(text.upper())

4. title()

Converts first letter of each word into capital letter.

text = "python programming"

print(text.title())

5. capitalize()

Capitalizes first letter only.

text = "python"

print(text.capitalize())

6. strip()

Removes spaces from both sides.

text = "   Python   "

print(text.strip())

7. lstrip()

Removes spaces from left side.

text = "   Python"

print(text.lstrip())

8. rstrip()

Removes spaces from right side.

text = "Python   "

print(text.rstrip())

9. replace()

Replaces old value with new value.

text = "I like Java"

print(text.replace("Java", "Python"))

10. find()

Returns index position of first occurrence.

text = "Python"

print(text.find("t"))

11. count()

Counts occurrences.

text = "banana"

print(text.count("a"))

12. startswith()

Checks beginning of string.

text = "Python"

print(text.startswith("Py"))

13. endswith()

Checks ending of string.

text = "Python"

print(text.endswith("on"))

14. split()

Splits string into list.

text = "Python Java C++"

print(text.split())

15. join()

Joins list items into string

words = ['Python', 'Java', 'C++']

print(" - ".join(words))

16. isalpha()

Checks if all characters are alphabets.

text = "Python"

print(text.isalpha())

17. isdigit()

Checks if all characters are digits.

text = "12345"

print(text.isdigit())

18. isalnum()

Checks if string is alphanumeric.

text = "Python123"

print(text.isalnum())

19. isspace()

Checks if string contains only spaces.

text = "   "

print(text.isspace())

20. swapcase()

Changes uppercase to lowercase and vice versa.

text = "PyThOn"

print(text.swapcase())

7. Escape Characters

8. Important Programs
Program 2: Check Palindrome

text = input("Enter string: ")

if text == text[::-1]:
    print("Palindrome")
else:
    print("Not Palindrome")

Program 3: Count Vowels

text = input("Enter string: ")

count = 0

for ch in text.lower():
    if ch in "aeiou":
        count += 1

print("Total vowels:", count)

Quick Revision Table

Conclusion

Strings are one of the most important data types in Python.
They are widely used for:

• Text processing
• Input handling
• Data formatting
• Pattern searching
• File handling

Practice string functions regularly for better programming skills