How many bytes in " signed short " data type in c ? -

firstly,i tried sizeof(signed short), output 2 bytes.

but when tried check hex representation of signed short, turns out 4 bytes :

#include <stdio.h>  void main(){  signed short  test  ;  test=-17; /* number */  printf(" -17 when viewed signed short hexa \t %x\n ", test);  }` 

the output :

-17 when viewed signed short hexa      ffffffef 

ffffffef means 32 bits not 16 bits !

the specifier %x requires integer, , compiler automatically converts short int before print it.
if type signed type compiler performs sign extension, means if value negative propagate upper word of int. i.e. if have -17=0xffef short converting int have oxffffffef. if had positive value 17=0x11, 0x11 int , print out 0x11.
test made makes no sense.
on other hand size of type (int, short, etc) compiler and/or machine dependent, , using sizeof() operator correct way check size.