This example sets the code page of the process to 850.

#define INCL_DOSNLS       /* National Language Support values */
#define INCL_DOSERRORS    /* DOS Error values */
#include <os2.h>
#include <stdio.h>


int main(VOID) {
APIRET rc      = NO_ERROR;

rc = DosSetProcessCp(850);

if (rc != NO_ERROR) {
  printf("DosSetProcessCp error: return code = %u\n", rc);
  return 1;
}

return NO_ERROR;
}