x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
MBSTOWCS(3) Linux Programmer's Manual MBSTOWCS(3)
NAME
mbstowcs - convert a multibyte string to a wide-character string
SYNOPSIS
#include <stdlib.h>
size_t mbstowcs(wchar_t *dest, const char *src, size_t n);
DESCRIPTION
If dest is not NULL, the mbstowcs() function converts the multibyte
string src to a wide-character string starting at dest. At most n wide
characters are written to dest. The conversion starts in the initial
state. The conversion can stop for three reasons:
1. An invalid multibyte sequence has been encountered. In this case,
(size_t) -1 is returned.
2. n non-L'\0' wide characters have been stored at dest. In this case,
the number of wide characters written to dest is returned, but the
shift state at this point is lost.
3. The multibyte string has been completely converted, including the
terminating null wide character ('\0'). In this case, the number of
wide characters written to dest, excluding the terminating null wide
character, is returned.
The programmer must ensure that there is room for at least n wide char-
acters at dest.
If dest is NULL, n is ignored, and the conversion proceeds as above,
except that the converted wide characters are not written out to mem-
ory, and that no length limit exists.
In order to avoid the case 2 above, the programmer should make sure n
is greater than or equal to mbstowcs(NULL,src,0)+1.
RETURN VALUE
The mbstowcs() function returns the number of wide characters that make
up the converted part of the wide-character string, not including the
terminating null wide character. If an invalid multibyte sequence was
encountered, (size_t) -1 is returned.
CONFORMING TO
C99.
NOTES
The behavior of mbstowcs() depends on the LC_CTYPE category of the cur-
rent locale.
The function mbsrtowcs(3) provides a better interface to the same func-
tionality.
EXAMPLE
The program below illustrates the use of mbstowcs(), as well as some of
the wide character classification functions. An example run is the
following:
$ ./t_mbstowcs de_DE.UTF-8 GruBe!
Length of source string (excluding terminator):
8 bytes
6 multibyte characters
Wide character string is: GruBe! (6 characters)
G alpha upper
r alpha lower
u alpha lower
B alpha lower
e alpha lower
! !alpha
Program source
#include <locale.h>
#include <wchar.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
size_t mbslen; /* Number of multibyte characters in source */
wchar_t *wcs; /* Pointer to converted wide character string */
wchar_t *wp;
if (argc < 3) {
fprintf(stderr, "Usage: %s <locale> <string>\n", argv[0]);
exit(EXIT_FAILURE);
}
/* Apply the specified locale */
if (setlocale(LC_ALL, argv[1]) == NULL) {
perror("setlocale");
exit(EXIT_FAILURE);
}
/* Calculate the length required to hold argv[2] converted to
a wide character string */
mbslen = mbstowcs(NULL, argv[2], 0);
if (mbslen == (size_t) -1) {
perror("mbstowcs");
exit(EXIT_FAILURE);
}
/* Describe the source string to the user */
printf("Length of source string (excluding terminator):\n");
printf(" %zu bytes\n", strlen(argv[2]));
printf(" %zu multibyte characters\n\n", mbslen);
/* Allocate wide character string of the desired size. Add 1
to allow for terminating null wide character (L'\0'). */
wcs = calloc(mbslen + 1, sizeof(wchar_t));
if (wcs == NULL) {
perror("calloc");
exit(EXIT_FAILURE);
}
/* Convert the multibyte character string in argv[2] to a
wide character string */
if (mbstowcs(wcs, argv[2], mbslen + 1) == (size_t) -1) {
perror("mbstowcs");
exit(EXIT_FAILURE);
}
printf("Wide character string is: %ls (%zu characters)\n",
wcs, mbslen);
/* Now do some inspection of the classes of the characters in
the wide character string */
for (wp = wcs; *wp != 0; wp++) {
printf(" %lc ", (wint_t) *wp);
if (!iswalpha(*wp))
printf("!");
printf("alpha ");
if (iswalpha(*wp)) {
if (iswupper(*wp))
printf("upper ");
if (iswlower(*wp))
printf("lower ");
}
putchar('\n');
}
exit(EXIT_SUCCESS);
}
SEE ALSO
mblen(3), mbsrtowcs(3), mbtowc(3), wctomb(3), wcstombs(3)
COLOPHON
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GNU 2014-03-18 MBSTOWCS(3)
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