Stream Input and Output

┌──────────────────────────────────────────────────────────────────────┐
│A stream can be accessed either by byte-based or by wchar_t based.    │
│From an Internationalization's view point, wide-based access is       │
│recommended.                                                          │
└──────────────────────────────────────────────────────────────────────┘

In the IBM Visual Age C++ for OS/2, all input and output are mapped into logical data streams, either in text or in binary. An application can access a text stream with multibyte based operations or wide character based operations. By using wide-based operations, the application can read and write wide strings in the same manner as multibyte strings. Moreover, wide-character will make the application encoding and code page independent.

Coresspondence between byte-based and wide-based stream I/O functions. Equivalent stdio I/O functions are available respectively.

┌────────────────────┬────────────────────┬─────────────────────────┐
│byte-based          │wide-based          │Descriptions             │
├────────────────────┼────────────────────┼─────────────────────────┤
│getc/getchar        │getwc/getwchar      │Read a (wide) character  │
│                    │                    │from the stdio.          │
├────────────────────┼────────────────────┼─────────────────────────┤
│fgetc               │fgetwc              │Read a (wide) character  │
│                    │                    │from a specified input   │
│                    │                    │stream.                  │
├────────────────────┼────────────────────┼─────────────────────────┤
│fgets               │fgetws              │Read a (wide) string from│
│                    │                    │a specified input stream.│
├────────────────────┼────────────────────┼─────────────────────────┤
│putc/putchar        │putwc/putwchar      │Prints a (wide) character│
│                    │                    │to the stdio.            │
├────────────────────┼────────────────────┼─────────────────────────┤
│fputc               │fputwc              │Prints a (wide) character│
│                    │                    │to a specified output    │
│                    │                    │stream.                  │
├────────────────────┼────────────────────┼─────────────────────────┤
│fputs               │fputws              │Prints a (wide) string to│
│                    │                    │a specified output       │
│                    │                    │stream.                  │
├────────────────────┼────────────────────┼─────────────────────────┤
│ungetc              │ungetwc             │Pushes a (wide) character│
│                    │                    │back to a specified input│
│                    │                    │stream.                  │
└────────────────────┴────────────────────┴─────────────────────────┘

 ...
#include <stdio.h>
#include <wchar.h>

 ...
char* readProdFile()
{
FILE* fh;
wchar_t awcBuf[PROD_REC_MAXLEN+2];     /* +2 for '\n' & '\0'      */

    ...
   if( (fh = fopen( pszFnameProd, "r" )) == NULL )
   {
      logError( ERR_FILE_OPEN, MPFROMP(pszFnameProd) );
      return NULL;
   }

   while( fgetws( awcBuf, PROD_REC_MAXLEN+2, fh ) != NULL )
   {
       ...
   }
}

Note: Once you apply the wide-I/O functions to a stream, using non-wide-character functions on the same stream results in an unexpected error in the ungetwc() function.