int main( int argc, char **argv )

#include <windows.h>
#include <shellapi.h>

int WndMain() {
  int argc;
  wchar_t **argv = CommandLineToArgvW( GetCommandLine(), &argc );

#include <stdio.h>
#include <stdlib.h>

#define then

int main( int argc, char **argv ) {

  FILE *f;
  unsigned long  v = 0;
  unsigned short i = 0;
  char sig[ 4 ];

  if (argc != 2) {
    printf( "%s",
      "usage:\n"
      "  chss EXEFILE\n\n"

      "  Changes the subsystem type of the named exe file and reports the new\n"
      "  status: console or gui.\n\n"

      "  The file MUST be a PE32 or PE32+. No checking is done to verify that!\n"
      );
    return 0;
    }

  if ((f = fopen( argv[ 1 ], "rb+" )) == NULL) {
    fprintf( stderr, "Couldn't open %s", argv[ 1 ] );
    return 1;
    }

  /* addr of PE header signature */
  fseek( f, 60, SEEK_SET );
  fread( &v, 4, 1, f );

  fseek( f, v, SEEK_SET );
  fread( sig, 4, 1, f );
  if ((sig[ 0 ] != 'P') || (sig[ 1 ] != 'E') || (sig[ 2 ] != 0) || (sig[ 3 ] != 0)) {
    fprintf( stderr, "%s is not a PE32 or PE32+", argv[ 1 ] );
    return 1;
    }

  /* addr of subsystem code */
  v += 4 + 20 + 68;

  /* get current code */
  fseek( f, v, SEEK_SET );
  fread( &i, 2, 1, f );

  if (i == 3) 
    then {
      i = 2;
      printf( "%s converted from CONSOLE to GUI subsystem\n", argv[ 1 ] );
      }
    else {
      i = 3;
      printf( "%s converted from GUI to CONSOLE subsystem\n", argv[ 1 ] );
      }

  fseek( f, v, SEEK_SET );
  fwrite( &i, 2, 1, f );

  fclose( f );

  return 0;
  }

#include "windows.h"

...
int main()
{
    HWND hWnd = GetConsoleWindow();
    ShowWindow(hWnd, SW_HIDE);

    return 0;
}