Python String Handling

Hello Friends,

String Handling in Python

A string in Python is a sequence of characters enclosed within single quotes (' '), double quotes (" "), or triple quotes (''' ''' or """ """). Strings are used to store and manipulate text data.

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Creating Strings

name = "Python"
message = 'Welcome to Python'
paragraph = """Python is easy
and powerful"""

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Accessing Characters in a String

Strings are indexed starting from 0.

text = "Python"

print(text[0])
print(text[3])

Output:

P
h

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String Slicing

Slicing is used to extract a portion of a string.

text = "Python Programming"

print(text[0:6])
print(text[7:])
print(text[:6])
print(text[-11:])

Output:

Python
Programming
Python
Programming

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String Immutability

Strings are immutable, meaning they cannot be changed after creation.

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

Correct Way:

text = "Python"
text = "J" + text[1:]
print(text)

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Common String Methods

Changing Case

text = "Python Programming"

print(text.upper())
print(text.lower())
print(text.title())

Removing Whitespaces

text = "  Python  "

print(text.strip())
print(text.lstrip())
print(text.rstrip())

Searching in Strings

text = "Python Programming"

print(text.find("Python"))
print(text.count("o"))

Replacing Text

text = "I like Java"
text = text.replace("Java", "Python")
print(text)

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Checking String Content

text = "Python123"

print(text.isalpha())
print(text.isdigit())
print(text.isalnum())

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Splitting and Joining Strings

Split

text = "Python,Java,C++"
languages = text.split(",")
print(languages)

Join

languages = ["Python", "Java", "C++"]
text = " | ".join(languages)
print(text)

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String Formatting

Using f-strings (Recommended)

name = "Chandan"
age = 36

print(f"My name is {name} and I am {age} years old")

Using format()

print("My name is {} and I am {} years old".format(name, age))

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Iterating Over a String

text = "Python"

for char in text:
    print(char)

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String Comparison

a = "python"
b = "Python"

print(a == b)
print(a.lower() == b.lower())

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Real-Life Examples

Example 1: Validate Email

email = "test@gmail.com"

if "@" in email and "." in email:
    print("Valid Email")
else:
    print("Invalid Email")

Example 2: Count Words

text = "Python is easy to learn"
words = text.split()
print(len(words))

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Common Mistakes

• Trying to modify a string directly
• Forgetting string methods return new strings
• Incorrect indexing

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Summary

• Strings store text data
• Strings are immutable
• Python provides many built-in string methods
• f-strings are the best way for formatting