Standard I/O
[C Runtime Library.]

Collaboration diagram for Standard I/O:

Detailed Description

Standard stream interface to Nut/OS devices.

 #include <stdio.h>

In contrast to the standard, Nut/OS streams do not maintain there own buffers. Any input or output buffering is done in the device driver.

Nut/OS will not associate the standard streams stdin, stdout and stderr to a device when starting the application. Instead, freopen() can be used by the application to redirect any of these stream to any previously opened file, device or connected socket.

As an extension to the standard, many function come in an additional flavour with _P appended to their name. These functions accept specific parameters pointing into program space.

Output Call Graph

Input Call Graph

Defines

#define EOF

End of file.

#define _IOFBF

Fully buffered.

#define _IOLBF

Line buffered.

#define _IONBF

Unbuffered.

#define stdin

Standard input stream.

#define stdout

Standard output stream.

#define stderr

Standard error output stream.

#define CF_LONG

#define CF_SUPPRESS

#define CF_SIGNOK

#define CF_NDIGITS

#define CF_PFXOK

#define CF_NZDIGITS

#define CF_DPTOK

#define CF_EXPOK

#define CT_CHAR

#define CT_STRING

#define CT_INT

#define CT_FLOAT

#define BUF

#define PADSIZE

#define ALT

#define LADJUST

#define LONGINT

#define ZEROPAD

Typedefs

typedef __iobuf FILE

Stream structure type.

Functions

void clearerr (FILE *stream)

Reset error status of a stream.

int fclose (FILE *stream)

Close a stream.

void fcloseall (void)

Close all open streams.

FILE * _fdopen (int fd, CONST char *mode)

Open a stream associated with a file, device or socket descriptor.

int feof (FILE *stream)

Test if a stream reached the end of file.

int ferror (FILE *stream)

Test for an error on a stream.

int fflush (FILE *stream)

Flush a stream.

int fgetc (FILE *stream)

Read a character from a stream.

char * fgets (char *buffer, int count, FILE *stream)

Read a line from a stream.

int _fileno (FILE *stream)

Get the file descriptor associated with a stream.

void _flushall (void)

Flushes all streams.

int _fmode (CONST char *mode)

FILE * fopen (CONST char *name, CONST char *mode)

Open a stream.

int fprintf (FILE *stream, CONST char *fmt,...)

Print formatted data to a stream.

int fprintf_P (FILE *stream, PGM_P fmt,...)

Print formatted data to a stream.

int fpurge (FILE *stream)

Purge a stream, i.e. discards the input buffer.

int fputc (int c, FILE *stream)

Write a character to a stream.

int fputs (CONST char *string, FILE *stream)

Write a string to a stream.

int fputs_P (PGM_P string, FILE *stream)

Write a string from progam memory to a stream.

size_t fread (void *buffer, size_t size, size_t count, FILE *stream)

Read data from a stream.

FILE * freopen (CONST char *name, CONST char *mode, FILE *stream)

Reassign a stream.

int fscanf (FILE *stream, CONST char *fmt,...)

Read formatted data from a stream.

int fscanf_P (FILE *stream, PGM_P fmt,...)

Read formatted data from a stream.

int fseek (FILE *stream, long offset, int origin)

Move read/write position of a stream.

long ftell (FILE *stream)

Return the read/write position of a stream.

size_t fwrite (CONST void *data, size_t size, size_t count, FILE *stream)

Write data to a stream.

size_t fwrite_P (PGM_P data, size_t size, size_t count, FILE *stream)

Write data from program space to a stream.

int getc (FILE *stream)

Read a character from a stream.

int getchar (void)

Read a character from a standard input.

int _getf (int _getb(int, void *, size_t), int fd, CONST char *fmt, va_list ap)

Read formatted data using a given input function.

char * gets (char *buffer)

Get a line from the standard input stream.

int printf (CONST char *fmt,...)

Print formatted data to the standard output stream.

int printf_P (PGM_P fmt,...)

Print formatted output to the standard output stream.

int putc (int c, FILE *stream)

Write a character to a stream.

int putchar (int c)

Write a character to standard output.

int _putf (int _putb(int, CONST void *, size_t), int fd, CONST char *fmt, va_list ap)

Write formatted data using a given output function.

int puts (CONST char *string)

Write a string to stdout.

int puts_P (PGM_P string)

Write a string from program memory to stdout.

int scanf (CONST char *fmt,...)

Read formatted data from the standard input stream.

int scanf_P (PGM_P fmt,...)

Read formatted data from the standard input stream.

int sprintf (char *buffer, CONST char *fmt,...)

Write formatted data to a string.

int sprintf_P (char *buffer, PGM_P fmt,...)

Write formatted data to a string.

int sscanf (CONST char *string, CONST char *fmt,...)

Read formatted data from a string.

int sscanf_P (CONST char *string, CONST char *fmt,...)

Read formatted data from a string.

int ungetc (int c, FILE *stream)

Push a character back onto a stream.

int vfprintf (FILE *stream, CONST char *fmt, va_list ap)

Write argument list to a stream using a given format.

int vfprintf_P (FILE *stream, PGM_P fmt, va_list ap)

Write argument list to a stream using a given format.

int vfscanf (FILE *stream, CONST char *fmt, va_list ap)

Read formatted data from a stream.

int vfscanf_P (FILE *stream, PGM_P fmt, va_list ap)

Read formatted data from a stream.

int vsprintf (char *buffer, CONST char *fmt, va_list ap)

Write argument list to a string using a given format.

int vsprintf_P (char *buffer, PGM_P fmt, va_list ap)

Write argument list to a string using a given format.

int vsscanf (CONST char *string, CONST char *fmt, va_list ap)

Read formatted data from a string.

int vsscanf_P (CONST char *string, PGM_P fmt, va_list ap)

Read formatted data from a string.

Variables

FILE * __iob []

FILE * __iob [FOPEN_MAX]

Define Documentation

#define EOF

End of file.
Returned by an input or output operation when the end of a file is encountered. Some routines return this value to indicate an error.

Typedef Documentation

typedef struct __iobuf FILE

Stream structure type.
A pointer to this type is used for all standard I/O functions to specify a stream.

Note:
Applications should make any assumptions about the contents of this structure as it may change without further notice.

Function Documentation

FILE* _fdopen ( int fd,

CONST char * mode

)

Open a stream associated with a file, device or socket descriptor.

Parameters:

fd Descriptor of a previously opened file, device or connected socket.

mode Specifies the access mode.

"r" Read only.

"w" Write only.

"a" Write only at the end of file.

"r+" Read and write existing file.

"w+" Read and write, destroys existing file contents.

"a+" Read and write, preserves existing file contents.

"b" May be appended to any of the above strings to specify binary access.

Returns:
A pointer to the open stream or a null pointer to indicate an error.

int _fileno ( FILE * stream )

Get the file descriptor associated with a stream.
In contrast to other implementations, the standard streams stdin, stdout and stderr do not return 0, 1 and 2 resp.

Parameters:

stream Pointer to a previously opened stream.

Returns:
The file descriptor.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int _getf ( int _getb(int, void *, size_t),

int fd,

CONST char * fmt,

va_list ap

)

Read formatted data using a given input function.

Parameters:

_getb Input function for reading data.

fd Descriptor of a previously opened file, device or connected socket.

fmt Format string containing coversion specifications.

ap List of pointer arguments.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int _putf ( int _putb(int, CONST void *, size_t),

int fd,

CONST char * fmt,

va_list ap

)

Write formatted data using a given output function.

Parameters:

_putb Output function for writing data.

fd Descriptor of a previously opened file, device or connected socket.

fmt Format string containing conversion specifications.

ap List of arguments.

void clearerr ( FILE * stream )

Reset error status of a stream.

Parameters:

stream Pointer to a previously opened stream.

int fclose ( FILE * stream )

Close a stream.
The calling thread may be suspended until all buffered output data has been written.

Parameters:

stream Pointer to a previously opened stream.

Returns:
0 if the stream is successfully closed, EOF otherwise.

void fcloseall ( void )

Close all open streams.
The standard streams stdin, stdout and stderr are not closed.
The calling thread may be suspended until all buffered output data has been written.

int feof ( FILE * stream )

Test if a stream reached the end of file.

Parameters:

stream Pointer to a previously opened stream.

Returns:
0 if the current position is not the end of the file.

int ferror ( FILE * stream )

Test for an error on a stream.

Parameters:

stream Pointer to a previously opened stream.

Returns:
0 if no error occured.

int fflush ( FILE * stream )

Flush a stream.
The calling thread may be suspended until all buffered output data has been written.

Parameters:

stream Pointer to a previously opened stream.

Returns:
0 if the buffer was successfully flushed, EOF if an error occured.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fgetc ( FILE * stream )

Read a character from a stream.

Parameters:

stream Pointer to a previously opened stream.

Returns:
Character read or EOF to indicate an error or end of file.

Warning:
The function will not check, if the stream pointer points to a valid stream.

char* fgets ( char * buffer,

int count,

FILE * stream

)

Read a line from a stream.
Read at most one less than the specified number of characters from a stream or stop when a newline has been read.

Parameters:

buffer Pointer to the buffer that receives the data including the linefeed character.

count Maximum number of characters to read.

stream Pointer to a previously opened stream.

Returns:
Pointer to the given buffer or NULL to indicate an error or the end of the file.

Warning:
The function will not check, if the stream pointer points to a valid stream.

FILE* fopen ( CONST char * name,

CONST char * mode

)

Open a stream.

Parameters:

name The name of a registered device, optionally followed by a colon and a filename.

mode Specifies the access mode.

"r" Read only.

"w" Write only.

"a" Write only at the end of file.

"r+" Read and write existing file.

"w+" Read and write, destroys existing file contents.

"a+" Read and write, preserves existing file contents.

"b" May be appended to any of the above strings to specify binary access.

Returns:
A pointer to the open stream or a null pointer to indicate an error.

int fprintf ( FILE * stream,

CONST char * fmt,

...

)

Print formatted data to a stream.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string containing conversion specifications.

Returns:
The number of characters written or a negative value to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fprintf_P ( FILE * stream,

PGM_P fmt,

...

)

Print formatted data to a stream.
Similar to fprintf() except that the format string is located in program memory.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string in program space containing conversion specifications.

Returns:
The number of bytes written or a negative value to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.
Do not use this function with a debug device while running in interrupt context.

Examples:
httpd/httpserv.c, and tcps/tcps.c.

int fpurge ( FILE * stream )

Purge a stream, i.e. discards the input buffer.

Parameters:

stream Pointer to a previously opened stream.

Returns:
0 if the buffer was successfully purged, EOF if an error occured.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fputc ( int c,

FILE * stream

)

Write a character to a stream.

Parameters:

c Character to write.

stream Pointer to a previously opened stream.

Returns:
The character written or EOF to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fputs ( CONST char * string,

FILE * stream

)

Write a string to a stream.

Parameters:

stream Pointer to a previously opened stream.

string String to write.

Returns:
A non-negative value if successful or EOF to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fputs_P ( PGM_P string,

FILE * stream

)

Write a string from progam memory to a stream.
Similar to fputs() except that the string is located in program space.

Parameters:

stream Pointer to a previously opened stream.

string String in program memory to write.

Returns:
A non-negative value if successful or EOF to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.

Examples:
httpd/httpserv.c, tcps/tcps.c, and uart/uart.c.

size_t fread ( void * buffer,

size_t size,

size_t count,

FILE * stream

)

Read data from a stream.

Parameters:

buffer Pointer to the buffer that receives the data.

size Item size in bytes.

count Maximum number of items to read.

stream Pointer to a previously opened stream.

Returns:
The number of full items read, which may be less then the specified number.

Warning:
The function will not check, if the stream pointer points to a valid stream.

FILE* freopen ( CONST char * name,

CONST char * mode,

FILE * stream

)

Reassign a stream.

Parameters:

name The name of a registered device, optionally followed by a colon and a filename.

mode Specifies the access mode.

"r" Read only.

"w" Write only.

"a" Write only at the end of file.

"r+" Read and write existing file.

"w+" Read and write, destroys existing file contents.

"a+" Read and write, preserves existing file contents.

"b" May be appended to any of the above strings to specify binary access.

stream Pointer to a previously opened stream.

Returns:
A pointer to the open stream or a null pointer to indicate an error.

int fscanf ( FILE * stream,

CONST char * fmt,

...

)

Read formatted data from a stream.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fscanf_P ( FILE * stream,

PGM_P fmt,

...

)

Read formatted data from a stream.
Similar to fscanf() except that the format string is expected in program space.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string in program space containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int fseek ( FILE * stream,

long offset,

int origin

)

Move read/write position of a stream.

Parameters:

stream Pointer to a previously opened stream.

offset Number of bytes from initial position.

origin Initial position to seek from.

Returns:
0 if no error occured.

long ftell ( FILE * stream )

Return the read/write position of a stream.

Parameters:

stream Pointer to a previously opened stream.

Returns:
The current position.

size_t fwrite ( CONST void * data,

size_t size,

size_t count,

FILE * stream

)

Write data to a stream.

Parameters:

data Pointer to items to be written.

size Item size in bytes.

count Number of items to write.

stream Pointer to a previously opened stream.

Returns:
The number of items written, which may be less than the specified number.

Warning:
The function will not check, if the stream pointer points to a valid stream.

size_t fwrite_P ( PGM_P data,

size_t size,

size_t count,

FILE * stream

)

Write data from program space to a stream.
Similar to fwrite() except that the data is located in program memory.

Parameters:

data Pointer to items in program space to be written.

size Item size in bytes.

count Number of items to write.

stream Pointer to a previously opened stream.

Returns:
The number of items written, which may be less than the specified number.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int getc ( FILE * stream )

Read a character from a stream.
Same as fgetc().

Parameters:

stream Pointer to a previously opened stream.

Returns:
Character read or EOF to indicate an error or end of file.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int getchar ( void )

Read a character from a standard input.

Returns:
Character read or EOF to indicate an error or end of file.

char* gets ( char * buffer )

Get a line from the standard input stream.
Read characters from a stream until a newline has been read.

Parameters:

buffer Pointer to the buffer that receives the line excluding the linefeed character.

Returns:
The given argument on success, 0 otherwise.

Warning:
This function is potentially unsafe, because it may write pass the end of the buffer.

int printf ( CONST char * fmt,

...

)

Print formatted data to the standard output stream.

Parameters:

fmt Format string containing conversion specifications.

Returns:
The number of characters written or a negative value to indicate an error.

int printf_P ( PGM_P fmt,

...

)

Print formatted output to the standard output stream.
Similar to printf() except that the format string is located in program memory.

Parameters:

fmt Format string in program space containing conversion specifications.

Returns:
The number of characters written or a negative value to indicate an error.

Warning:
Do not use this function with a debug device while running in interrupt context.

Examples:
tcps/tcps.c.

int putc ( int c,

FILE * stream

)

Write a character to a stream.
Same as fputc().

Parameters:

c Character to write.

stream Pointer to a previously opened stream.

Returns:
The character written or EOF to indicate an error.

Warning:
The function will not check, if the stream pointer points to a valid stream.

int putchar ( int c )

Write a character to standard output.

Parameters:

c Character to write.

Returns:
The character written or EOF to indicate an error.

int puts ( CONST char * string )

Write a string to stdout.

Parameters:

string String to write.

Returns:
A non-negative value or EOF to indicate an error.

int puts_P ( PGM_P string )

Write a string from program memory to stdout.
Similar to puts() except that the string is located in program memory.

Parameters:

string String in program memory to write.

Returns:
A non-negative value or EOF to indicate an error.

int scanf ( CONST char * fmt,

...

)

Read formatted data from the standard input stream.

Parameters:

fmt Format string containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, ff an error occurs or if the end of the stream is reached before the first conversion.

int scanf_P ( PGM_P fmt,

...

)

Read formatted data from the standard input stream.
Similar to scanf() except that the format string is located in program space.

Parameters:

fmt Format string containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, ff an error occurs or if the end of the stream is reached before the first conversion.

int sprintf ( char * buffer,

CONST char * fmt,

...

)

Write formatted data to a string.

Parameters:

buffer Pointer to a buffer that receives the output string.

fmt Format string containing conversion specifications.

Returns:
The number of characters written or a negative value to indicate an error.

int sprintf_P ( char * buffer,

PGM_P fmt,

...

)

Write formatted data to a string.
Similar to sprintf() except that the format string is located in program memory.

Parameters:

buffer Pointer to a buffer that receives the output string.

fmt Format string in program space containing conversion specifications.

Returns:
The number of characters written or a negative value to indicate an error.

int sscanf ( CONST char * string,

CONST char * fmt,

...

)

Read formatted data from a string.

Parameters:

string Pointer to the string that contains the data.

fmt Format string containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int sscanf_P ( CONST char * string,

CONST char * fmt,

...

)

Read formatted data from a string.
Similar to sscanf() except that the format string is located in program space.

Parameters:

string Pointer to the string that contains the data.

fmt Format string in program space containing conversion specifications.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int ungetc ( int c,

FILE * stream

)

Push a character back onto a stream.

Parameters:

c Character to push back.

stream Pointer to a previously opened stream.

Warning:
Only a single character can be pushed back. Any previously pushed and not yet read character will be lost.

int vfprintf ( FILE * stream,

CONST char * fmt,

va_list ap

)

Write argument list to a stream using a given format.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string containing conversion specifications.

ap List of arguments.

Returns:
The number of characters written or a negative value to indicate an error.

int vfprintf_P ( FILE * stream,

PGM_P fmt,

va_list ap

)

Write argument list to a stream using a given format.
Similar to vfprintf() except that the format string is located in program memory.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string in program space containing conversion specifications.

ap List of arguments.

Returns:
The number of characters written or a negative value to indicate an error.

int vfscanf ( FILE * stream,

CONST char * fmt,

va_list ap

)

Read formatted data from a stream.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string containing conversion specifications.

ap List of pointer arguments.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int vfscanf_P ( FILE * stream,

PGM_P fmt,

va_list ap

)

Read formatted data from a stream.
Similar to vfscanf() except that the format string is located in program space.

Parameters:

stream Pointer to a previously opened stream.

fmt Format string in program space containing conversion specifications.

ap List of pointer arguments.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int vsprintf ( char * buffer,

CONST char * fmt,

va_list ap

)

Write argument list to a string using a given format.

Parameters:

buffer Pointer to a buffer that receives the output string.

fmt Format string containing conversion specifications.

ap List of arguments.

Returns:
The number of characters written or a negative value to indicate an error.

int vsprintf_P ( char * buffer,

PGM_P fmt,

va_list ap

)

Write argument list to a string using a given format.
Similar to vsprintf() except that the format string is located in program memory.

Parameters:

buffer Pointer to a buffer that receives the output string.

fmt Format string in program space containing conversion specifications.

ap List of arguments.

Returns:
The number of characters written or a negative value to indicate an error.

int vsscanf ( CONST char * string,

CONST char * fmt,

va_list ap

)

Read formatted data from a string.

Parameters:

string Pointer to a string that contains the data.

fmt Format string containing conversion specifications.

ap List of pointer arguments.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

int vsscanf_P ( CONST char * string,

PGM_P fmt,

va_list ap

)

Read formatted data from a string.
Similar to vsscanf() except that the format string is located in program space.

Parameters:

string Pointer to a string that contains the data.

fmt Format string in program space containing conversion specifications.

ap List of pointer arguments.

Returns:
The number of fields successfully converted and assigned. The return value is EOF, if an error occurs or if the end of the stream is reached before the first conversion.

Programmable Gateways

Standard I/O [C Runtime Library.]

Detailed Description

Defines

Typedefs

Functions

Variables

Define Documentation

Typedef Documentation

Function Documentation

Standard I/O
[C Runtime Library.]