0xC00xDF

0xC00xDF is an identifier that has appeared in discussions as an example of malformed hexadecimal notation. It is not a valid numeric literal in common programming languages because hexadecimal literals are written with a single 0x prefix followed by digits 0-9 and letters A-F. The string 0xC00xDF contains an additional 'x' inside, which makes it invalid as a number.

In terms of interpretation, 0xC00xDF can be seen as a typographical anomaly, a misprint for a nearby valid value, or a teaching aid to highlight parsing errors and input validation requirements. Some readers speculate it might be intended as 0xC0CDF or 0xC00ADF, but such substitutions are not standardized. In practice, the token is most often discussed as an example rather than a functional code.

Contexts where it appears include programming tutorials, discussions about lexical analysis, and puzzles or obfuscated-code challenges. In these settings, the string serves to illustrate how automated tools should handle unexpected characters within numeric literals, or how different languages tokenize strings versus numbers. If treated strictly as data, 0xC00xDF would be interpreted as plain text rather than a numeric value, depending on the language and parser configuration.

See also: hexadecimal notation, numeric literals, parsing and lexical analysis.