Endianness — why do chars put in an Int16 print backwards?

Question

The following C code, compiled and run in XCode:

UInt16 chars = \'ab\';
printf(\"\\nchars: %2.2s\", (char*)&chars);

prints \'ba\', rather t

Answer 1

Multicharacter character literals are implementation-defined:

C99 6.4.4.4p10: "The value of an integer character constant containing more than one character (e.g., 'ab'), or containing a character or escape sequence that does not map to a single-byte execution character, is implementation-defined."

gcc and icl print ba on Windows 7. tcc prints a and drops the second letter altogether...