| 64 bit | 32 bit | 16 bit | 8 bit | |
|---|---|---|---|---|
| A (accumulator) | RAX |
EAX |
AX |
AL |
| B (base, addressing) | RBX |
EBX |
BX |
BL |
| C (counter, iterations) | RCX |
ECX |
CX |
CL |
| D (data) | RDX |
EDX |
DX |
DL |
Devon Smith devo8604
Earnestly
/ c99_ub_list.rst
Last active
January 27, 2026 09:44
C99 List of Undefined Behavior (193 Cases)
From N1256: (See http://port70.net/~nsz/c/c99/n1256.html#J.2)
- A "shall" or "shall not" requirement that appears outside of a constraint is violated (clause 4).
- A nonempty source file does not end in a new-line character which is not immediately preceded by a backslash character or ends in a partial preprocessing token or comment (5.1.1.2).
- Token concatenation produces a character sequence matching the syntax of a universal character name (5.1.1.2).
- A program in a hosted environment does not define a function named
mainusing one of the specified forms (5.1.2.2.1). - A character not in the basic source character set is encountered in a source file, except in an identifier, a character constant, a string literal, a header name, a comment, or a preprocessing token that is never converted to a token (5.2.1).
- An identifier, comment, string literal, character constant, or header name contains an invalid multibyte character or does not