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MBSTOWCS(3)                Linux Programmer's ManualMBSTOWCS(3)NAME       mbstowcs - convert a multibyte string to a wide-character stringSYNOPSIS       #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 sequence of characters in the       string src shall begin in the initial shift 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 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.ATTRIBUTES       For an  explanation  of  the  terms  used  in  this  section,  see  at-tributes(7).       +-----------+---------------+---------+       |Interface  | Attribute     | Value   |       +-----------+---------------+---------+       |mbstowcs() | Thread safety | MT-Safe |       +-----------+---------------+---------+CONFORMING TO       POSIX.1-2001, POSIX.1-2008, C99.NOTES       The behavior of mbstowcs() depends on the LC_CTYPE category of the cur-       rent locale.       The functionmbsrtowcs(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 Grusse!           Length of source string (excluding terminator):               8 bytes               6 multibyte characters           Wide character string is: Grusse! (6 characters)               G alpha upper               r alpha lower               u alpha lower               ss alpha lower               e alpha lower               ! !alpha   Program source       #include <wctype.h>       #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 ALSOmblen(3),mbsrtowcs(3),mbtowc(3),wcstombs(3),wctomb(3)COLOPHON       This  page  is  part of release 5.05 of the Linux man-pages project.  A       description of the project, information about reporting bugs,  and  the       latest     version     of     this    page,    can    be    found    at       https://www.kernel.org/doc/man-pages/.GNU                               2019-03-06MBSTOWCS(3)