voidclearerr(FILE*__stream)[extern]
Clear the error and end-of-file flags of stream.
intfclose(FILE*__stream)[extern]
This function closes stream, and disallows and further IO to and from it.
When using fdevopen() to setup the stream, a call to fclose() is needed in order to free the internal
resources allocated.
If the stream has been set up using fdev_setup_stream() or FDEV_SETUP_STREAM(), use fdev_close() instead.
It currently always returns 0 (for success).
FILE*fdevopen(int(*)(char,FILE*)put,int(*)(FILE*)get)
This function is a replacement for fopen().
It opens a stream for a device where the actual device implementation needs to be provided by the
application. If successful, a pointer to the structure for the opened stream is returned. Reasons for a
possible failure currently include that neither the put nor the get argument have been provided, thus
attempting to open a stream with no IO intent at all, or that insufficient dynamic memory is available to
establish a new stream.
If the put function pointer is provided, the stream is opened with write intent. The function passed as
put shall take two arguments, the first a character to write to the device, and the second a pointer to
FILE, and shall return 0 if the output was successful, and a nonzero value if the character could not be
sent to the device.
If the get function pointer is provided, the stream is opened with read intent. The function passed as
get shall take a pointer to FILE as its single argument, and return one character from the device, passed
as an int type. If an error occurs when trying to read from the device, it shall return _FDEV_ERR.Ifanend-of-fileconditionwasreachedwhilereadingfromthedevice,_FDEV_EOFshallbereturned.
If both functions are provided, the stream is opened with read and write intent.
The first stream opened with read intent is assigned to stdin, and the first one opened with write intent
is assigned to both, stdout and stderr.
fdevopen() uses calloc() (und thus malloc()) in order to allocate the storage for the new stream.
Note
If the macro __STDIO_FDEVOPEN_COMPAT_12 is declared before including <stdio.h>, a function prototype
for fdevopen() will be chosen that is backwards compatible with AVR-LibC version 1.2 and before. This
is solely intented for providing a simple migration path without the need to immediately change all
source code. Do not use for new code.
intfeof(FILE*__stream)[extern]
Test the end-of-file flag of stream. This flag can only be cleared by a call to clearerr().
intferror(FILE*__stream)[extern]
Test the error flag of stream. This flag can only be cleared by a call to clearerr().
intfflush(FILE*stream)[extern]
Flush stream.
This is a null operation provided for source-code compatibility only, as the standard IO implementation
currently does not perform any buffering.
intfgetc(FILE*__stream)[extern]
The function fgetc reads a character from stream. It returns the character, or EOF in case end-of-file
was encountered or an error occurred. The routines feof() or ferror() must be used to distinguish between
both situations.
char*fgets(char*__str,int__size,FILE*__stream)[extern]
Read at most size - 1 bytes from stream, until a newline character was encountered, and store the
characters in the buffer pointed to by str. Unless an error was encountered while reading, the string
will then be terminated with a NUL character.
If an error was encountered, the function returns NULL and sets the error flag of stream, which can be
tested using ferror(). Otherwise, a pointer to the string will be returned.
intfprintf(FILE*__stream,constchar*__fmt,...)[extern]
The function fprintf performs formatted output to stream. See vfprintf()fordetails.intfprintf_P(FILE*__stream,constchar*__fmt,...)[extern]
Variant of fprintf()thatusesafmtstringthatresidesinprogrammemory.intfputc(int__c,FILE*__stream)[extern]
The function fputc sends the character c (though given as type int) to stream. It returns the character,
or EOF in case an error occurred.
intfputs(constchar*__str,FILE*__stream)[extern]
Write the string pointed to by str to stream stream.
Returns 0 on success and EOF on error.
intfputs_P(constchar*__str,FILE*__stream)[extern]
Variant of fputs() where str resides in program memory.
size_tfread(void*__ptr,size_t__size,size_t__nmemb,FILE*__stream)[extern]
Read nmemb objects, size bytes each, from stream, to the buffer pointed to by ptr.
Returns the number of objects successfully read, i. e. nmemb unless an input error occured or end-of-file
was encountered. feof() and ferror() must be used to distinguish between these two conditions.
intfscanf(FILE*__stream,constchar*__fmt,...)[extern]
The function fscanf performs formatted input, reading the input data from stream.
See vfscanf() for details.
intfscanf_P(FILE*__stream,constchar*__fmt,...)[extern]
Variant of fscanf() using a fmt string in program memory.
size_tfwrite(constvoid*__ptr,size_t__size,size_t__nmemb,FILE*__stream)[extern]
Write nmemb objects, size bytes each, to stream. The first byte of the first object is referenced by ptr.
Returns the number of objects successfully written, i. e. nmemb unless an output error occured.
char*gets(char*__str)[extern]
Similar to fgets() except that it will operate on stream stdin, and the trailing newline (if any) will
not be stored in the string. It is the caller's responsibility to provide enough storage to hold the
characters read.
intprintf(constchar*__fmt,...)[extern]
The function printf performs formatted output to stream stdout. See vfprintf()fordetails.intprintf_P(constchar*__fmt,...)[extern]
Variant of printf()thatusesafmtstringthatresidesinprogrammemory.intputs(constchar*__str)[extern]
Write the string pointed to by str, and a trailing newline character, to stdout.
intputs_P(constchar*__str)[extern]
Variant of puts() where str resides in program memory.
intscanf(constchar*__fmt,...)[extern]
The function scanf performs formatted input from stream stdin.
See vfscanf() for details.
intscanf_P(constchar*__fmt,...)[extern]
Variant of scanf() where fmt resides in program memory.
intsnprintf(char*__s,size_t__n,constchar*__fmt,...)[extern]
Like sprintf(),butinsteadofassumingstobeofinfinitesize,nomorethanncharacters(includingthetrailingNULcharacter)willbeconvertedtos.
Returns the number of characters that would have been written to s if there were enough space.
intsnprintf_P(char*__s,size_t__n,constchar*__fmt,...)[extern]
Variant of snprintf()thatusesafmtstringthatresidesinprogrammemory.intsprintf(char*__s,constchar*__fmt,...)[extern]
Variant of printf()thatsendstheformattedcharacterstostrings.intsprintf_P(char*__s,constchar*__fmt,...)[extern]
Variant of sprintf()thatusesafmtstringthatresidesinprogrammemory.intsscanf(constchar*__buf,constchar*__fmt,...)[extern]
The function sscanf performs formatted input, reading the input data from the buffer pointed to by buf.
See vfscanf() for details.
intsscanf_P(constchar*__buf,constchar*__fmt,...)[extern]
Variant of sscanf() using a fmt string in program memory.
intungetc(int__c,FILE*__stream)[extern]
The ungetc() function pushes the character c (converted to an unsigned char) back onto the input stream
pointed to by stream. The pushed-back character will be returned by a subsequent read on the stream.
Currently, only a single character can be pushed back onto the stream.
The ungetc() function returns the character pushed back after the conversion, or EOF if the operation
fails. If the value of the argument c character equals EOF, the operation will fail and the stream will
remain unchanged.
intvfprintf(FILE*__stream,constchar*__fmt,va_list__ap)[extern]
vfprintf is the central facility of the printf family of functions. It outputs values to stream under
control of a format string passed in fmt. The actual values to print are passed as a variable argument
list ap.
vfprintf returns the number of characters written to stream, or EOF in case of an error. Currently, this
will only happen if stream has not been opened with write intent.
The format string is composed of zero or more directives: ordinary characters (not %), which are copied
unchanged to the output stream; and conversion specifications, each of which results in fetching zero or
more subsequent arguments. Each conversion specification is introduced by the % character. The arguments
must properly correspond (after type promotion) with the conversion specifier. After the %, the following
appear in sequence:
• Zero or more of the following flags:
• # The value should be converted to an 'alternate form'. For c, d, i, s, and u conversions, this
option has no effect. For o conversions, the precision of the number is increased to force the first
character of the output string to a zero (except if a zero value is printed with an explicit
precision of zero). For x and X conversions, a non-zero result has the string `0x' (or `0X' for X
conversions) prepended to it.
• 0 (zero) Zero padding. For all conversions, the converted value is padded on the left with zeros
rather than blanks. If a precision is given with a numeric conversion (d, i, o, u, i, x, and X), the
0 flag is ignored.
• - A negative field width flag; the converted value is to be left adjusted on the field boundary. The
converted value is padded on the right with blanks, rather than on the left with blanks or zeros. A -
overrides a 0 if both are given.
•
• + A sign must always be placed before a number produced by a signed conversion. A + overrides a space
if both are used.
• An optional decimal digit string specifying a minimum field width. If the converted value has fewer
characters than the field width, it will be padded with spaces on the left (or right, if the left-
adjustment flag has been given) to fill out the field width.
• An optional precision, in the form of a period . followed by an optional digit string. If the digit
string is omitted, the precision is taken as zero. This gives the minimum number of digits to appear
for d, i, o, u, x, and X conversions, or the maximum number of characters to be printed from a string
for s conversions.
• An optional l or h length modifier, that specifies that the argument for the d, i, o, u, x, or X
conversion is a 'long int' rather than int. The h is ignored, as 'short int' is equivalent to int.
• A character that specifies the type of conversion to be applied.
The conversion specifiers and their meanings are:
• diouxX The int (or appropriate variant) argument is converted to signed decimal (d and i), unsigned
octal (o), unsigned decimal (u), or unsigned hexadecimal (x and X) notation. The letters 'abcdef' are
used for x conversions; the letters 'ABCDEF' are used for X conversions. The precision, if any, gives
the minimum number of digits that must appear; if the converted value requires fewer digits, it is
padded on the left with zeros.
• p The void * argument is taken as an unsigned integer, and converted similarly as a %#x command would
do.
• c The int argument is converted to an 'unsigned char', and the resulting character is written.
• s The 'char *' argument is expected to be a pointer to an array of character type (pointer to a
string). Characters from the array are written up to (but not including) a terminating NUL character;
if a precision is specified, no more than the number specified are written. If a precision is given, no
null character need be present; if the precision is not specified, or is greater than the size of the
array, the array must contain a terminating NUL character.
• % A % is written. No argument is converted. The complete conversion specification is '%%'.
• eE The double argument is rounded and converted in the format '[-]d.ddde±dd' where there is one digit
before the decimal-point character and the number of digits after it is equal to the precision; if the
precision is missing, it is taken as 6; if the precision is zero, no decimal-point character appears.
An E conversion uses the letter 'E' (rather than 'e') to introduce the exponent. The exponent always
contains two digits; if the value is zero, the exponent is 00.
• fF The double argument is rounded and converted to decimal notation in the format '[-]ddd.ddd', where
the number of digits after the decimal-point character is equal to the precision specification. If the
precision is missing, it is taken as 6; if the precision is explicitly zero, no decimal-point character
appears. If a decimal point appears, at least one digit appears before it.
• gG The double argument is converted in style f or e (or F or E for G conversions). The precision
specifies the number of significant digits. If the precision is missing, 6 digits are given; if the
precision is zero, it is treated as 1. Style e is used if the exponent from its conversion is less than
-4 or greater than or equal to the precision. Trailing zeros are removed from the fractional part of
the result; a decimal point appears only if it is followed by at least one digit.
• S Similar to the s format, except the pointer is expected to point to a program-memory (ROM) string
instead of a RAM string.
In no case does a non-existent or small field width cause truncation of a numeric field; if the result of
a conversion is wider than the field width, the field is expanded to contain the conversion result.
Since the full implementation of all the mentioned features becomes fairly large, three different
flavours of vfprintf() can be selected using linker options. The default vfprintf() implements all the
mentioned functionality except floating point conversions. A minimized version of vfprintf() is available
that only implements the very basic integer and string conversion facilities, but only the # additional
option can be specified using conversion flags (these flags are parsed correctly from the format
specification, but then simply ignored). This version can be requested using the following compileroptions:
-Wl,-u,vfprintf -lprintf_min
If the full functionality including the floating point conversions is required, the following options
should be used:
-Wl,-u,vfprintf -lprintf_flt -lm
Limitations:
• The specified width and precision can be at most 255.
Notes:
• For floating-point conversions, if you link default or minimized version of vfprintf(), the symbol
? will be output and double argument will be skipped. So you output below will not be crashed. For
default version the width field and the 'pad to left' ( symbol minus ) option will work in this
case.
• The hh length modifier is ignored (char argument is promouted to int). More exactly, this
realization does not check the number of h symbols.
• But the ll length modifier will to abort the output, as this realization does not operate long long
arguments.
• The variable width or precision field (an asterisk * symbol) is not realized and will to abort the
output.
intvfprintf_P(FILE*__stream,constchar*__fmt,va_list__ap)[extern]
Variant of vfprintf()thatusesafmtstringthatresidesinprogrammemory.intvfscanf(FILE*stream,constchar*fmt,va_listap)[extern]
Formatted input. This function is the heart of the scanf family of functions.
Characters are read from stream and processed in a way described by fmt. Conversion results will be
assigned to the parameters passed via ap.
The format string fmt is scanned for conversion specifications. Anything that doesn't comprise a
conversion specification is taken as text that is matched literally against the input. White space in the
format string will match any white space in the data (including none), all other characters match only
itself. Processing is aborted as soon as the data and format string no longer match, or there is an error
or end-of-file condition on stream.
Most conversions skip leading white space before starting the actual conversion.
Conversions are introduced with the character %. Possible options can follow the %:
• a * indicating that the conversion should be performed but the conversion result is to be discarded; no
parameters will be processed from ap,
• the character h indicating that the argument is a pointer to short int (rather than int),
• the 2 characters hh indicating that the argument is a pointer to char (rather than int).
• the character l indicating that the argument is a pointer to long int (rather than int, for integer
type conversions), or a pointer to float (for floating point conversions),
In addition, a maximal field width may be specified as a nonzero positive decimal integer, which will
restrict the conversion to at most this many characters from the input stream. This field width is
limited to at most 255 characters which is also the default value (except for the c conversion that
defaults to 1).
The following conversion flags are supported:
• % Matches a literal % character. This is not a conversion.
• d Matches an optionally signed decimal integer; the next pointer must be a pointer to int.
• i Matches an optionally signed integer; the next pointer must be a pointer to int. The integer is read
in base 16 if it begins with 0x or 0X, in base 8 if it begins with 0, and in base 10 otherwise. Only
characters that correspond to the base are used.
• o Matches an octal integer; the next pointer must be a pointer to unsigned int.
• u Matches an optionally signed decimal integer; the next pointer must be a pointer to unsigned int.
• x Matches an optionally signed hexadecimal integer; the next pointer must be a pointer to unsigned int.
• f Matches an optionally signed floating-point number; the next pointer must be a pointer to float.
• e, g, F, E, G Equivalent to f.
• s Matches a sequence of non-white-space characters; the next pointer must be a pointer to char, and the
array must be large enough to accept all the sequence and the terminating NUL character. The input
string stops at white space or at the maximum field width, whichever occurs first.
• c Matches a sequence of width count characters (default 1); the next pointer must be a pointer to char,
and there must be enough room for all the characters (no terminating NUL is added). The usual skip of
leading white space is suppressed. To skip white space first, use an explicit space in the format.
• [ Matches a nonempty sequence of characters from the specified set of accepted characters; the next
pointer must be a pointer to char, and there must be enough room for all the characters in the string,
plus a terminating NUL character. The usual skip of leading white space is suppressed. The string is to
be made up of characters in (or not in) a particular set; the set is defined by the characters between
the open bracket [ character and a close bracket ] character. The set excludes those characters if the
first character after the open bracket is a circumflex ^. To include a close bracket in the set, make
it the first character after the open bracket or the circumflex; any other position will end the set.
The hyphen character - is also special; when placed between two other characters, it adds all
intervening characters to the set. To include a hyphen, make it the last character before the final
close bracket. For instance, [^]0-9-] means the set of everythingexceptclosebracket,zerothroughnine,andhyphen. The string ends with the appearance of a character not in the (or, with a circumflex,
in) set or when the field width runs out. Note that usage of this conversion enlarges the stack
expense.
• p Matches a pointer value (as printed by p in printf()); the next pointer must be a pointer to void.
• n Nothing is expected; instead, the number of characters consumed thus far from the input is stored
through the next pointer, which must be a pointer to int. This is not a conversion, although it can be
suppressed with the * flag.
These functions return the number of input items assigned, which can be fewer than provided for, or even
zero, in the event of a matching failure. Zero indicates that, while there was input available, no
conversions were assigned; typically this is due to an invalid input character, such as an alphabetic
character for a d conversion. The value EOF is returned if an input failure occurs before any conversion
such as an end-of-file occurs. If an error or end-of-file occurs after conversion has begun, the number
of conversions which were successfully completed is returned.
By default, all the conversions described above are available except the floating-point conversions and
the width is limited to 255 characters. The float-point conversion will be available in the extended
version provided by the library libscanf_flt.a. Also in this case the width is not limited (exactly, it
is limited to 65535 characters). To link a program against the extended version, use the following
compiler flags in the link stage:
-Wl,-u,vfscanf -lscanf_flt -lm
A third version is available for environments that are tight on space. In addition to the restrictions of
the standard one, this version implements no %[ specification. This version is provided in the library
libscanf_min.a, and can be requested using the following options in the link stage:
-Wl,-u,vfscanf -lscanf_min -lm
intvfscanf_P(FILE*__stream,constchar*__fmt,va_list__ap)[extern]
Variant of vfscanf() using a fmt string in program memory.
intvprintf(constchar*__fmt,va_list__ap)[extern]
The function vprintf performs formatted output to stream stdout, taking a variable argument list as in
vfprintf().
See vfprintf() for details.
intvscanf(constchar*__fmt,va_list__ap)[extern]
The function vscanf performs formatted input from stream stdin, taking a variable argument list as in
vfscanf().
See vfscanf() for details.
intvsnprintf(char*__s,size_t__n,constchar*__fmt,va_listap)[extern]
Like vsprintf(),butinsteadofassumingstobeofinfinitesize,nomorethanncharacters(includingthetrailingNULcharacter)willbeconvertedtos.
Returns the number of characters that would have been written to s if there were enough space.
intvsnprintf_P(char*__s,size_t__n,constchar*__fmt,va_listap)[extern]
Variant of vsnprintf()thatusesafmtstringthatresidesinprogrammemory.intvsprintf(char*__s,constchar*__fmt,va_listap)[extern]
Like sprintf()buttakesavariableargumentlistforthearguments.intvsprintf_P(char*__s,constchar*__fmt,va_listap)[extern]
Variant of vsprintf()thatusesafmtstringthatresidesinprogrammemory.
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