From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/c/string%2Fmultibyte%2Fwctomb.html | 82 ++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 devdocs/c/string%2Fmultibyte%2Fwctomb.html (limited to 'devdocs/c/string%2Fmultibyte%2Fwctomb.html') diff --git a/devdocs/c/string%2Fmultibyte%2Fwctomb.html b/devdocs/c/string%2Fmultibyte%2Fwctomb.html new file mode 100644 index 00000000..0c17d262 --- /dev/null +++ b/devdocs/c/string%2Fmultibyte%2Fwctomb.html @@ -0,0 +1,82 @@ +

wctomb, wctomb_s

Defined in header <stdlib.h> 
int wctomb( char *s, wchar_t wc );
+		 (1) 
errno_t wctomb_s( int *restrict status, char *restrict s, rsize_t ssz, wchar_t wc );
+		 (2) (since C11)
+1) Converts a wide character wc to multibyte encoding and stores it (including any shift sequences) in the char array whose first element is pointed to by s. No more than MB_CUR_MAX characters are stored. The conversion is affected by the current locale's LC_CTYPE category.
+ If wc is the null character, the null byte is written to s, preceded by any shift sequences necessary to restore the initial shift state.
+ If s is a null pointer, this function resets the global conversion state and determines whether shift sequences are used.
+2) Same as (1), except that the result is returned in the out-parameter status and the following errors are detected at runtime and call the currently installed constraint handler function:
+
+
    +
  • ssz is less than the number of bytes that would be written (unless s is null)
    • +
  • ssz is greater than RSIZE_MAX (unless s is null)
    • +
  • s is a null pointer but ssz is not zero
    • +
+
As with all bounds-checked functions, wctomb_s only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including <stdlib.h>.
+
+

Notes

Each call to wctomb updates the internal global conversion state (a static object of type mbstate_t, known only to this function). If the multibyte encoding uses shift states, this function is not reentrant. In any case, multiple threads should not call wctomb without synchronization: wcrtomb or wctomb_s may be used instead.

+

Unlike most bounds-checked functions, wctomb_s does not null-terminate its output, because it is designed to be used in loops that process strings character-by-character.

+

Parameters

+ + + + +
s - pointer to the character array for output
wc - wide character to convert
ssz - maximum number of bytes to write to s (size of the array s)
status - pointer to an out-parameter where the result (length of the multibyte sequence or the shift sequence status) will be stored

Return value

+1) If s is not a null pointer, returns the number of bytes that are contained in the multibyte representation of wc or -1 if wc is not a valid character.
+ If s is a null pointer, resets its internal conversion state to represent the initial shift state and returns ​0​ if the current multibyte encoding is not state-dependent (does not use shift sequences) or a non-zero value if the current multibyte encoding is state-dependent (uses shift sequences).
+2) zero on success, in which case the multibyte representation of wc is stored in s and its length is stored in *status, or, if s is null, the shift sequence status is stored in status). Non-zero on encoding error or runtime constraint violation, in which case (size_t)-1 is stored in *status. The value stored in *status never exceeds MB_CUR_MAX +

Example

#include <stdio.h>
+#include <stdlib.h>
+#include <locale.h>
+ 
+void demo(wchar_t wc)
+{
+    const char* dep = wctomb(NULL, wc) ? "Yes" : "No";
+    printf("State-dependent encoding? %s.\n", dep);
+ 
+    char mb[MB_CUR_MAX];
+    int len = wctomb(mb, wc);
+    printf("wide char '%lc' -> multibyte char [", wc);
+    for (int idx = 0; idx < len; ++idx)
+        printf("%s%#2x", idx ? " " : "", (unsigned char)mb[idx]);
+    printf("]\n");
+}
+ 
+int main(void)
+{
+    setlocale(LC_ALL, "en_US.utf8");
+    printf("MB_CUR_MAX = %zu\n", MB_CUR_MAX);
+    demo(L'A');
+    demo(L'\u00df');
+    demo(L'\U0001d10b');
+}

Possible output:

+
MB_CUR_MAX = 6
+State-dependent encoding? No.
+wide char 'A' -> multibyte char [0x41]
+State-dependent encoding? No.
+wide char 'ß' -> multibyte char [0xc3 0x9f]
+State-dependent encoding? No.
+wide char '𝄋' -> multibyte char [0xf0 0x9d 0x84 0x8b]

References

See also

+ + +
converts the next multibyte character to wide character
(function)
+
(C95)(C11)
 converts a wide character to its multibyte representation, given state
(function)
C++ documentation for wctomb
+

+ © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
+ https://en.cppreference.com/w/c/string/multibyte/wctomb +

+
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