What is CONSTANT_CASE?
CONSTANT_CASE (also called SCREAMING_SNAKE_CASE, MACRO_CASE, or simply UPPER_SNAKE_CASE) uses all uppercase letters with underscores between words. It's the convention for compile-time constants, environment variables, and preprocessor macros in most languages.
The visual loudness signals "this value doesn't change at runtime" — useful for spotting magic numbers, configuration keys, and API tokens at a glance.
When to use CONSTANT_CASE
- Compile-time constants in C, C++, Java, C#, Python, Ruby, JavaScript.
- Environment variables —
DATABASE_URL,API_KEY,MAX_RETRIES. - C macros and preprocessor directives —
#define MAX_BUFFER_SIZE 1024. - Configuration keys in ini-style files.
- Enum members in some style guides — though many languages now prefer PascalCase for enum members.
- HTTP header names in CGI variables —
HTTP_USER_AGENT.
How CONSTANT_CASE conversion works
- Input is tokenized using the smart tokenizer.
- Each word is uppercased.
- Words are joined with a single underscore between them.
Worked examples
| Input | CONSTANT_CASE |
|---|---|
max retry count |
MAX_RETRY_COUNT |
api base url |
API_BASE_URL |
default timeout |
DEFAULT_TIMEOUT |
is production mode |
IS_PRODUCTION_MODE |
Related case formats
snake_case
→ Convert text to snake_case
UPPERCASE→ Convert text to UPPERCASE
kebab-case→ Convert text to kebab-case
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