Upper/Lower Case Converter

Introduction to English Letters

The English alphabet is a set of Latin letters used to write English and other languages. It consists of 26 letters divided into uppercase and lowercase forms. Uppercase letters are typically used for constants, abbreviations, or specific formatting requirements, while lowercase letters are more common in general text.

ASCII Introduction

ASCII (American Standard Code for Information Interchange) is a character encoding standard for electronic communication. It includes English letters (both cases), numbers, punctuation marks, and control characters, typically ranging from 0 to 127.

Uppercase Letters

In ASCII, uppercase Latin letters A-Z are encoded from 65 (A) to 90 (Z). Uppercase letters are commonly used for constants, abbreviations, and specific formatting requirements.

Lowercase Letters

Lowercase Latin letters a-z are encoded from 97 (a) to 122 (z). Lowercase letters are used for most regular text as they are more natural for reading.

Convert Uppercase to Lowercase

To convert uppercase to lowercase, add 32 to the ASCII code. For example, 'A' (65) becomes 'a' (97).

Convert Lowercase to Uppercase

To convert lowercase to uppercase, subtract 32 from the ASCII code. For example, 'a' (97) becomes 'A' (65).

Python Case Conversion Example

# Upper to lower：
text = "Hello World!"
upper_text = text.upper()
print(upper_text)  # "HELLO WORLD!"

# lower to upper：
lower_text = text.lower()
print(lower_text)  # "hello world!"

    

Java Case Conversion Example

public class CaseConverter {
    public static void main(String[] args) {
        String text = "Hello World!";

        // To upper
        String upperText = text.toUpperCase();
        System.out.println(upperText);  // "HELLO WORLD!"

        // To lower
        String lowerText = text.toLowerCase();
        System.out.println(lowerText);  // "hello world!"
    }
}