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Standard library header <cwchar> - cppreference.com

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This header was originally in the C standard library as <wchar.h>.

This header is part of the null-terminated wide and multibyte strings libraries. It also provides some C-style I/O functions and conversion from C-style Date.

Macros

implementation-defined null pointer constant
(macro constant) [edit]
a non-character value of type std::wint_t used to indicate errors
(macro constant)
the smallest valid value of wchar_t
(macro constant)
the largest valid value of wchar_t
(macro constant)

Types

conversion state information necessary to iterate multibyte character strings
(class) [edit]
unsigned integer type returned by the sizeof operator
(typedef) [edit]
wint_t integer type that can hold any valid wide character and at least one more value
calendar time type
(class) [edit]

Functions

String manipulation
copies one wide string to another
(function) [edit]
copies a certain amount of wide characters from one string to another
(function) [edit]
appends a copy of one wide string to another
(function) [edit]
appends a certain amount of wide characters from one wide string to another
(function) [edit]
transform a wide string so that wcscmp would produce the same result as wcscoll
(function) [edit]
String examination
returns the length of a wide string
(function) [edit]
compares two wide strings
(function) [edit]
compares a certain amount of characters from two wide strings
(function) [edit]
compares two wide strings in accordance to the current locale
(function) [edit]
finds the first occurrence of a wide character in a wide string
(function) [edit]
finds the last occurrence of a wide character in a wide string
(function) [edit]
returns the length of the maximum initial segment that consists
of only the wide characters found in another wide string
(function) [edit]
returns the length of the maximum initial segment that consists
of only the wide not found in another wide string
(function) [edit]
finds the first location of any wide character in one wide string, in another wide string
(function) [edit]
finds the first occurrence of a wide string within another wide string
(function) [edit]
finds the next token in a wide string
(function) [edit]
Wide character array manipulation
copies a certain amount of wide characters between two non-overlapping arrays
(function) [edit]
copies a certain amount of wide characters between two, possibly overlapping, arrays
(function) [edit]
compares a certain amount of wide characters from two arrays
(function) [edit]
finds the first occurrence of a wide character in a wide character array
(function) [edit]
copies the given wide character to every position in a wide character array
(function) [edit]
Multibyte/wide character conversion
checks if the std::mbstate_t object represents initial shift state
(function) [edit]
widens a single-byte narrow character to wide character, if possible
(function) [edit]
narrows a wide character to a single-byte narrow character, if possible
(function) [edit]
returns the number of bytes in the next multibyte character, given state
(function) [edit]
converts the next multibyte character to wide character, given state
(function) [edit]
converts a wide character to its multibyte representation, given state
(function) [edit]
converts a narrow multibyte character string to wide string, given state
(function) [edit]
converts a wide string to narrow multibyte character string, given state
(function) [edit]
Input/Output
gets a wide character from a file stream
(function) [edit]
gets a wide string from a file stream
(function) [edit]
writes a wide character to a file stream
(function) [edit]
writes a wide string to a file stream
(function) [edit]
reads a wide character from stdin
(function) [edit]
writes a wide character to stdout
(function) [edit]
puts a wide character back into a file stream
(function) [edit]
switches a file stream between wide character I/O and narrow character I/O
(function) [edit]
reads formatted wide character input from stdin, a file stream or a buffer
(function) [edit]

(C++11)(C++11)(C++11)

 reads formatted wide character input from stdin, a file stream
or a buffer using variable argument list
(function) [edit]
prints formatted wide character output to stdout, a file stream or a buffer
(function) [edit]
prints formatted wide character output to stdout, a file stream
or a buffer using variable argument list
(function) [edit]
String conversions
converts a std::tm object to custom wide string textual representation
(function) [edit]
converts a wide string to an integer value
(function) [edit]
converts a wide string to an unsigned integer value
(function) [edit]
converts a wide string to a floating-point value
(function) [edit]

Notes

Synopsis

namespace std {
  using size_t =    /* see description */; // freestanding
  using mbstate_t = /* see description */; // freestanding
  using wint_t =    /* see description */; // freestanding

  struct tm;

  int fwprintf(FILE* stream, const wchar_t* format, ...);
  int fwscanf(FILE* stream, const wchar_t* format, ...);
  int swprintf(wchar_t* s, size_t n, const wchar_t* format, ...);
  int swscanf(const wchar_t* s, const wchar_t* format, ...);
  int vfwprintf(FILE* stream, const wchar_t* format, va_list arg);
  int vfwscanf(FILE* stream, const wchar_t* format, va_list arg);
  int vswprintf(wchar_t* s, size_t n, const wchar_t* format, va_list arg);
  int vswscanf(const wchar_t* s, const wchar_t* format, va_list arg);
  int vwprintf(const wchar_t* format, va_list arg);
  int vwscanf(const wchar_t* format, va_list arg);
  int wprintf(const wchar_t* format, ...);
  int wscanf(const wchar_t* format, ...);
  wint_t fgetwc(FILE* stream);
  wchar_t* fgetws(wchar_t* s, int n, FILE* stream);
  wint_t fputwc(wchar_t c, FILE* stream);
  int fputws(const wchar_t* s, FILE* stream);
  int fwide(FILE* stream, int mode);
  wint_t getwc(FILE* stream);
  wint_t getwchar();
  wint_t putwc(wchar_t c, FILE* stream);
  wint_t putwchar(wchar_t c);
  wint_t ungetwc(wint_t c, FILE* stream);
  double wcstod(const wchar_t* nptr, wchar_t** endptr);
  float wcstof(const wchar_t* nptr, wchar_t** endptr);
  long double wcstold(const wchar_t* nptr, wchar_t** endptr);
  long int wcstol(const wchar_t* nptr, wchar_t** endptr, int base);
  long long int wcstoll(const wchar_t* nptr, wchar_t** endptr, int base);
  unsigned long int wcstoul(const wchar_t* nptr, wchar_t** endptr, int base);
  unsigned long long int wcstoull(const wchar_t* nptr, wchar_t** endptr, int base);
  wchar_t* wcscpy(wchar_t* s1, const wchar_t* s2);                // freestanding
  wchar_t* wcsncpy(wchar_t* s1, const wchar_t* s2, size_t n);     // freestanding
  wchar_t* wmemcpy(wchar_t* s1, const wchar_t* s2, size_t n);     // freestanding
  wchar_t* wmemmove(wchar_t* s1, const wchar_t* s2, size_t n);    // freestanding
  wchar_t* wcscat(wchar_t* s1, const wchar_t* s2);                // freestanding
  wchar_t* wcsncat(wchar_t* s1, const wchar_t* s2, size_t n);     // freestanding
  int wcscmp(const wchar_t* s1, const wchar_t* s2);               // freestanding
  int wcscoll(const wchar_t* s1, const wchar_t* s2);
  int wcsncmp(const wchar_t* s1, const wchar_t* s2, size_t n);    // freestanding
  size_t wcsxfrm(wchar_t* s1, const wchar_t* s2, size_t n);
  int wmemcmp(const wchar_t* s1, const wchar_t* s2, size_t n);    // freestanding
  const wchar_t* wcschr(const wchar_t* s, wchar_t c);             // freestanding
  wchar_t* wcschr(wchar_t* s, wchar_t c);                         // freestanding
  size_t wcscspn(const wchar_t* s1, const wchar_t* s2);           // freestanding
  const wchar_t* wcspbrk(const wchar_t* s1, const wchar_t* s2);   // freestanding
  wchar_t* wcspbrk(wchar_t* s1, const wchar_t* s2);               // freestanding
  const wchar_t* wcsrchr(const wchar_t* s, wchar_t c);            // freestanding
  wchar_t* wcsrchr(wchar_t* s, wchar_t c);                        // freestanding
  size_t wcsspn(const wchar_t* s1, const wchar_t* s2);            // freestanding
  const wchar_t* wcsstr(const wchar_t* s1, const wchar_t* s2);    // freestanding
  wchar_t* wcsstr(wchar_t* s1, const wchar_t* s2);                // freestanding
  wchar_t* wcstok(wchar_t* s1, const wchar_t* s2, wchar_t** ptr); // freestanding
  const wchar_t* wmemchr(const wchar_t* s, wchar_t c, size_t n);  // freestanding
  wchar_t* wmemchr(wchar_t* s, wchar_t c, size_t n);              // freestanding
  size_t wcslen(const wchar_t* s);                                // freestanding
  wchar_t* wmemset(wchar_t* s, wchar_t c, size_t n);              // freestanding
  size_t wcsftime(wchar_t* s, size_t maxsize, const wchar_t* format, const tm* timeptr);
  wint_t btowc(int c);
  int wctob(wint_t c);

  // multibyte / wide string and character conversion functions
  int mbsinit(const mbstate_t* ps);
  size_t mbrlen(const char* s, size_t n, mbstate_t* ps);
  size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t* ps);
  size_t wcrtomb(char* s, wchar_t wc, mbstate_t* ps);
  size_t mbsrtowcs(wchar_t* dst, const char** src, size_t len, mbstate_t* ps);
  size_t wcsrtombs(char* dst, const wchar_t** src, size_t len, mbstate_t* ps);
}

#define NULL      /* see description */ // freestanding
#define WCHAR_MAX /* see description */ // freestanding
#define WCHAR_MIN /* see description */ // freestanding
#define WEOF      /* see description */ // freestanding

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 345 C++98 std::tm was not provided in <cwchar> provided