std::vwprintf, std::vfwprintf, std::vswprintf
Defined in header <cwchar>
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||
int vwprintf( const wchar_t* format, va_list vlist ); |
(1) | |
int vfwprintf( std::FILE* stream, const wchar_t* format, va_list vlist ); |
(2) | |
int vswprintf( wchar_t* buffer, std::size_t buf_size, const wchar_t* format, va_list vlist ); |
(3) | |
Loads the data from locations, defined by vlist
,, converts them to wide string equivalents and writes the results to a variety of sinks.
stream
.buffer
. At most size-1 wide characters are written followed by null wide character.Contents |
[edit] Parameters
stream | - | output wide stream to write to |
buffer | - | pointer to a wide string to write to |
buf_size | - | maximum number of wide characters to write |
format | - | pointer to a null-terminated wide string specifying how to interpret the data |
vlist | - | variable argument list containing the data to print. |
The format string consists of ordinary wide characters (except %
), which are copied unchanged into the output stream, and conversion specifications. Each conversion specification has the following format:
- introductory
%
character.
- introductory
- (optional) one or more flags that modify the behavior of the conversion:
-
-
: the result of the conversion is left-justified within the field (by default it is right-justified). -
+
: the sign of signed conversions is always prepended to the result of the conversion (by default the result is preceded by minus only when it is negative). - space: if the result of a signed conversion does not start with a sign character, or is empty, space is prepended to the result. It is ignored if
+
flag is present. -
#
: alternative form of the conversion is performed. See the table below for exact effects otherwise the behavior is undefined. -
0
: for integer and floating-point number conversions, leading zeros are used to pad the field instead of space characters. For integer numbers it is ignored if the precision is explicitly specified. For other conversions using this flag results in undefined behavior. It is ignored if-
flag is present.
-
- (optional) integer value or
*
that specifies minimum field width. The result is padded with space characters (by default), if required, on the left when right-justified, or on the right if left-justified. In the case when*
is used, the width is specified by an additional argument of type int, which appears before the argument to be converted and the argument supplying precision if one is supplied. If the value of the argument is negative, it results with the-
flag specified and positive field width (Note: This is the minimum width: The value is never truncated.).
- (optional) integer value or
- (optional)
.
followed by integer number or*
, or neither that specifies precision of the conversion. In the case when*
is used, the precision is specified by an additional argument of type int, which appears before the argument to be converted, but after the argument supplying minimum field width if one is supplied. If the value of this argument is negative, it is ignored. If neither a number nor*
is used, the precision is taken as zero. See the table below for exact effects of precision.
- (optional)
- (optional) length modifier that specifies the size of the argument (in combination with the conversion format specifier, it specifies the type of the corresponding argument).
- conversion format specifier.
The following format specifiers are available:
Conversion Specifier |
Explanation | Expected Argument Type | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Length Modifier→ | hh | h | none | l | ll | j | z | t | L | |
Only available since C++11→ | Yes | Yes | Yes | Yes | Yes | |||||
%
|
Writes literal % . The full conversion specification must be %% .
|
N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
c
|
Writes a single character.
|
N/A | N/A | int |
std::wint_t |
N/A | N/A | N/A | N/A | N/A |
s
|
Writes a character string.
|
N/A | N/A | char* |
wchar_t* |
N/A | N/A | N/A | N/A | N/A |
d i
|
Converts a signed integer into decimal representation [-]dddd.
|
signed char |
short |
int |
long |
long long |
※ |
N/A | ||
o
|
Converts an unsigned integer into octal representation oooo.
|
unsigned char |
unsigned short |
unsigned int |
unsigned long |
unsigned long long |
unsigned version of std::ptrdiff_t |
N/A | ||
x X
|
Converts an unsigned integer into hexadecimal representation hhhh.
|
N/A | ||||||||
u
|
Converts an unsigned integer into decimal representation dddd.
|
N/A | ||||||||
f F (C++11)
|
Converts floating-point number to the decimal notation in the style [-]ddd.ddd.
|
N/A | N/A | double |
double (C++11) |
N/A | N/A | N/A | N/A | long double |
e E
|
Converts floating-point number to the decimal exponent notation.
|
N/A | N/A | N/A | N/A | N/A | N/A | |||
a A
(C++11) |
Converts floating-point number to the hexadecimal exponent notation.
|
N/A | N/A | N/A | N/A | N/A | N/A | |||
g G
|
Converts floating-point number to decimal or decimal exponent notation depending on the value and the precision.
|
N/A | N/A | N/A | N/A | N/A | N/A | |||
n
|
Returns the number of characters written so far by this call to the function.
|
signed char* |
short* |
int* |
long* |
long long* |
※ |
N/A | ||
p
|
Writes an implementation defined character sequence defining a pointer. |
N/A | N/A | void* |
N/A | N/A | N/A | N/A | N/A | N/A |
Notes | ||||||||||
The floating-point conversion functions convert infinity to Not-a-number is converted to The conversions The conversion specifier used to print char, unsigned char, signed char, short, and unsigned short expects promoted types of default argument promotions, but before printing its value will be converted to char, unsigned char, signed char, short, and unsigned short. It is safe to pass values of these types because of the promotion that takes place when a variadic function is called. The correct conversion specifications for the fixed-width character types (std::int8_t, etc) are defined in the header <cinttypes> (although PRIdMAX, PRIuMAX, etc is synonymous with The memory-writing conversion specifier There is a sequence point after the action of each conversion specifier; this permits storing multiple If a conversion specification is invalid, the behavior is undefined. |
[edit] Return value
size
.[edit] Notes
While narrow strings provide std::vsnprintf, which makes it possible to determine the required output buffer size, there is no equivalent for wide strings, and in order to determine the buffer size, the program may need to call std::vswprintf
, check the result value, and reallocate a larger buffer, trying again until successful.
[edit] Example
This section is incomplete Reason: no example |
[edit] See also
prints formatted output to stdout, a file stream or a buffer using variable argument list (function) | |
prints formatted wide character output to stdout, a file stream or a buffer (function) | |
C documentation for vwprintf, vfwprintf, vswprintf
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