Main differences between ASCII and Unicode:
1. Encoding Range:
- ASCII: Uses 7-bit binary, can represent 128 characters
- Unicode: Uses 16 bits or more, can represent 1,114,112 characters
2. Character Coverage:
- ASCII: Only contains English letters, numbers, basic symbols, and control characters
- Unicode: Contains characters, symbols, and emojis from all languages in the world
3. Storage Space:
- ASCII: Each character is fixed at 1 byte
- Unicode: Under UTF-8 encoding, English characters are 1 byte, Chinese characters are 3 bytes
- Unicode: Under UTF-16 encoding, common characters are 2 bytes, supplementary characters are 4 bytes
4. Compatibility:
- ASCII is a subset of Unicode, the first 128 characters are identical
- Unicode is backward compatible with ASCII
5. Application Scenarios:
- ASCII: Suitable for pure English text, simple network protocols
- Unicode: Suitable for international applications, multilingual support, modern software development
Selection Recommendations:
- Processing only English data: ASCII is sufficient
- Need to support multiple languages: Must use Unicode
- Modern development environment: Recommend using Unicode (UTF-8)