16-bit signed binary integer with extern "C"

#include <stdio.h>
#include <stdlib.h>
extern "C" {void COBRTN
  (short int);}

int main()
{
  short int x;
  x=5;
  COBRTN(x);    /* x by value */
  exit(0);
}

IDENTIFICATION DIVISION.
PROGRAM-ID. COBRTN.
ENVIRONMENT DIVISION.
DATA DIVISION.
LINKAGE SECTION.
01 X PIC S9(4) BINARY.
PROCEDURE DIVISION USING BY VALUE X.
     DISPLAY X.
     GOBACK.
END PROGRAM COBRTN.