mbrtowc.gml

来自「开放源码的编译器open watcom 1.6.0版的源代码」· GML 代码 · 共 156 行

.func mbrtowc _fmbrtowc
#include <wchar.h>
int mbrtowc( wchar_t *pwc, const char *s,
             size_t n, mbstate_t *ps );
.if &farfnc eq 1 .do begin
int _fmbrtowc( wchar_t __far *pwc, const char __far *s,
               size_t n, mbstate_t __far *ps );
.do end
.funcend
.desc begin
If
.arg s
is a null pointer, the &func function determines the number of bytes
necessary to enter the initial shift state (zero if encodings are not
state-dependent or if the initial conversion state is described).
In this case, the value of the
.arg pwc
argument will be ignored, and the resulting state described will be
the initial conversion state.
.np
If
.arg s
is not a null pointer, the &func function determines the number of
bytes that are contained in the multibyte character (plus any leading
shift sequences) pointed to by
.arg s,
produces the value of the corresponding wide character and then, if
.arg pwc
is not a null pointer, stores that value in the object pointed to by
.arg pwc.
If the corresponding wide character is the null wide character, the
resulting state described will be the initial conversion state.
.im farparm
.im mbcrstrt
.desc end
.return begin
If
.arg s
is a null pointer, the &func function returns the number of bytes
necessary to enter the initial shift state.
The value returned will not be greater than that of the
.kw MB_CUR_MAX
macro.
.np
If
.arg s
is not a null pointer, the &func function returns the first of the
following that applies:
.begnote
.termhd1 Value
.termhd2 Meaning
.note 0
if the next
.arg n
or fewer bytes form the multibyte character that corresponds to the
null wide character.
.note >0
if the next
.arg n
or fewer bytes form a valid multibyte character; the value returned is
the number of bytes that constitute that multibyte character.
.note -2
if the next
.arg n
bytes form an incomplete (but potentially valid) multibyte character,
and all
.arg n
bytes have been processed; it is unspecified whether this can occur
when the value of
.arg n
is less than that of the
.kw MB_CUR_MAX
macro.
.note -1
if an encoding error occurs (when the next
.arg n
or fewer bytes do not form a complete and valid multibyte character);
the value of the macro
.kw EILSEQ
will be stored in
.kw errno,
but the conversion state will be unchanged.
.endnote
.return end
.see begin
.im seembc &function.
.see end
.exmp begin
#include <stdio.h>
#include <wchar.h>
#include <mbctype.h>
#include <errno.h>


const char chars[] = {
    ' ',
    '.',
    '1',
    'A',
    0x81,0x40, /* double-byte space */
    0x82,0x60, /* double-byte A */
    0x82,0xA6, /* double-byte Hiragana */
    0x83,0x42, /* double-byte Katakana */
    0xA1,      /* single-byte Katakana punctuation */
    0xA6,      /* single-byte Katakana alphabetic */
    0xDF,      /* single-byte Katakana alphabetic */
    0xE0,0xA1, /* double-byte Kanji */
    0x00
};
.exmp break
void main()
  {
    int         i, j, k;
    wchar_t     pwc;

    _setmbcp( 932 );
    i = mbrtowc( NULL, NULL, MB_CUR_MAX, NULL );
    printf( "Number of bytes to enter "
            "initial shift state = %d\n", i );
    j = 1;
    for( i = 0; j > 0; i += j ) {
      j = mbrtowc( &pwc, &chars[i], MB_CUR_MAX, NULL );
      printf( "%d bytes in character ", j );
      if( errno == EILSEQ ) {
        printf( " - illegal multibyte character\n" );
      } else {
        if( j == 0 ) {
          k = 0;
        } else if ( j == 1 ) {
          k = chars[i];
        } else if( j == 2 ) {
          k = chars[i]<<8 | chars[i+1];
        }
        printf( "(%#6.4x->%#6.4x)\n", k, pwc );
      }
    }
  }
.exmp output
Number of bytes to enter initial shift state = 0
1 bytes in character (0x0020->0x0020)
1 bytes in character (0x002e->0x002e)
1 bytes in character (0x0031->0x0031)
1 bytes in character (0x0041->0x0041)
2 bytes in character (0x8140->0x3000)
2 bytes in character (0x8260->0xff21)
2 bytes in character (0x82a6->0x3048)
2 bytes in character (0x8342->0x30a3)
1 bytes in character (0x00a1->0xff61)
1 bytes in character (0x00a6->0xff66)
1 bytes in character (0x00df->0xff9f)
2 bytes in character (0xe0a1->0x720d)
0 bytes in character (  0000->  0000)
.exmp end
.class ANSI
.system