#define MACRO(abc, def) {#def ## #abc} char result[10] = MACRO(abc, def);
Standard input is empty
prog.cpp:3:33: error: pasting ""def"" and ""abc"" does not give a valid preprocessing token
char result[10] = MACRO(abc, def);
^
prog.cpp:1:27: note: in definition of macro ‘MACRO’
#define MACRO(abc, def) {#def ## #abc}
^
Standard output is empty