Case Conversion Methods in Python
Case Conversion Methods in Python (Syntax + Examples)
Python provides several built-in string methods to convert text between different cases (uppercase, lowercase, title case, etc.). Below are the key methods with syntax and examples:
1. upper() – Convert to Uppercase
Purpose: Converts all characters in a string to uppercase.
Syntax:
python
string.upper()
Examples:
python
text = "Hello, World!" print(text.upper()) # Output: "HELLO, WORLD!" filename = "data.txt" print(filename.upper()) # Output: "DATA.TXT"
2. lower() – Convert to Lowercase
Purpose: Converts all characters in a string to lowercase.
Syntax:
python
string.lower()
Examples:
python
text = "PyThOn Is FuN" print(text.lower()) # Output: "python is fun" email = "USER@EXAMPLE.COM" print(email.lower()) # Output: "user@example.com"
3. capitalize() – Capitalize First Letter
Purpose: Converts the first character to uppercase and the rest to lowercase.
Syntax:
python
string.capitalize()
Examples:
python
text = "hello world" print(text.capitalize()) # Output: "Hello world" name = "aLiCe" print(name.capitalize()) # Output: "Alice"
4. title() – Convert to Title Case
Purpose: Capitalizes the first letter of each word (like a title).
Syntax:
python
string.title()
Examples:
python
text = "python programming is fun" print(text.title()) # Output: "Python Programming Is Fun" book = "the great gatsby" print(book.title()) # Output: "The Great Gatsby"
5. swapcase() – Swap Cases
Purpose: Swaps uppercase letters to lowercase and vice versa.
Syntax:
python
string.swapcase()
Examples:
python
text = "Hello, WoRLD!" print(text.swapcase()) # Output: "hELLO, WOrld!" code = "PyThOn" print(code.swapcase()) # Output: "pYtHoN"
6. casefold() – Aggressive Lowercase (Unicode Support)
Purpose: Similar to lower(), but more aggressive (handles special Unicode characters).
Syntax:
python
string.casefold()
Examples:
python
text = "Straße" # German for "street" print(text.casefold()) # Output: "strasse" (lowercase + special handling) word = "İstanbul" print(word.casefold()) # Output: "i̇stanbul" (better for case-insensitive comparisons)
Summary Table
| Method | Purpose | Example |
|---|---|---|
upper() | Convert to uppercase | "hello".upper() → "HELLO" |
lower() | Convert to lowercase | "WORLD".lower() → "world" |
capitalize() | Capitalize first letter | "python".capitalize() → "Python" |
title() | Convert to title case | "hello world".title() → "Hello World" |
swapcase() | Swap uppercase/lowercase | "PyThOn".swapcase() → "pYtHoN" |
casefold() | Strong lowercase (Unicode) | "Straße".casefold() → "strasse" |
These methods are useful for text normalization, comparisons, and formatting. Let me know if you need more details! 🚀