This chapter provides reference material for the standard IO API:
Standard IO Functions
Standard IO Provider Functions
Application-Defined Function
The header files StdIOPalm.h and StdIOProvider.h declare the standard IO API. For more information on using the standard IO API, see the chapter "Standard IO Applications"in the Palm OS Programmer's Companion, vol. I.
Standard IO Functions

The macros and functions in this section enable standard IO.
fgetc

Purpose
Macro that calls Siofgetc to return the next character from the input stream.
Prototype
fgetc (fs)
Parameters
-> fs | An input stream from which to read the next character. You can specify only the value stdin for this parameter; alternate streams are not currently implemented. |
Result
The next character from the input stream. The return value EOF indicates an error occurred.
fgets

Purpose
Macro that calls Siofgets to return a string from the input stream.
Prototype
fgets (strP, maxChars, fs)
Parameters
<- strP | A pointer to the returned string. |
-> maxChars | The number of characters to read from the input stream, plus one for the null terminator. |
-> fs | An input stream from which to read the next character. You can specify only the value stdin for this parameter; alternate streams are not currently implemented. |
Result
A pointer to the string read from the input stream. If an error or EOF occurs before any characters are read, returns NULL.
Comments
The returned string is always terminated by a null character.
fprintf

Purpose
Macro that calls Siofprintf to write formatted output to an output stream.
Prototype
fprintf (fs, formatP, ...)
Parameters
-> fs | An output stream to which to write the formatted output. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> ... | Zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings). Returns a negative number if there is an error.
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported.
fputc

Purpose
Macro that calls Siofputc to write a character to the output stream.
Prototype
fputc (c, fs)
Parameters
-> c | A character to write to the output stream. |
-> fs | An output stream to which to write the character. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
Result
The character that was written. If an error occurs, the value EOF is returned.
fputs

Purpose
Macro that calls Siofputs to write a string to the output stream.
Prototype
fputs (strP, fs)
Parameters
-> strP | A pointer to the string to write. |
-> fs | An output stream to which to write the string. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
Result
Returns 0 on success and the value EOF on error.
getchar

Purpose
Macro that calls Siofgetc to read the next character from the stdin input stream.
Prototype
getchar ()
Result
The next character from the input stream. The return value EOF indicates an error occurred.
gets

Purpose
Macro that calls Siogets to read a string from the stdin input stream.
Prototype
gets (strP)
Parameters
<- strP | A pointer to the returned string. |
Result
A pointer to the string read from the input stream. If an error or EOF occurs before any characters are read, returns NULL.
Comments
The returned string does not include a null terminator. You must ensure that the input line, if any, is sufficiently short to fit in the string.
printf

Purpose
Macro that calls Sioprintf to write formatted output to the stdout output stream.
Prototype
printf (formatP, ...)
Parameters
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> ... | Zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings).
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported. Returns a negative number if there is an error.
putc

Purpose
Macro that calls Siofputc to write a character to the output stream.
Prototype
putc (c, fs)
Parameters
-> c | A character to write to the output stream. |
-> fs | An output stream to which to write the character. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
Result
The character that was written. If an error occurs, the value EOF is returned.
putchar

Purpose
Macro that calls Siofputc to write a character to the stdout output stream.
Prototype
putchar (c)
Parameters
-> c | A character to write to the stdout output stream. |
Result
The character that was written. If an error occurs, the value EOF is returned.
puts

Purpose
Macro that calls Sioputs to write a string to the output stream stdout.
Prototype
puts (strP)
Parameters
-> strP | A pointer to the string to write to stdout. |
Result
Returns a nonnegative value on success and the value EOF on error.
SioAddCommand

Purpose
Adds a built-in command that is supplied by the standard IO provider application.
Prototype
void SioAddCommand (const Char *cmdStr, SioMainProcPtr cmdProcP)
Parameters
-> cmdStr | Pointer to a string that is the command name. |
-> cmdProcP | Pointer to the command entry point function (the SioMain function). |
Result
Returns nothing.
Comments
This routine is useful for registering a command that is inside the standard IO provider application instead of in its own database.
This routine must be used to test commands under the Simulator since it can't launch application databases.
Siofgetc

Return the next character from the input stream.
Prototype
Int16 Siofgetc (FILE *fs)
Parameters
-> fs | An input stream from which to read the next character. You can specify only the value stdin for this parameter; alternate streams are not currently implemented. |
Result
The next character from the input stream. The return value EOF indicates an error occurred.
See Also
fgetc
Siofgets

Purpose
Return a string from the input stream.
Prototype
Char *Siofgets (Char *strP, UInt16 maxChars, FILE *fs)
Parameters
<- strP | A pointer to the returned string. |
-> maxChars | The number of characters to read from the input stream, plus one for the null terminator. |
-> fs | An input stream from which to read the next character. You can specify only the value stdin for this parameter; alternate streams are not currently implemented. |
Result
A pointer to the string read from the input stream. If an error or EOF occurs before any characters are read, returns NULL.
Comments
The returned string is always terminated by a null character.
See Also
fgets
Siofprintf

Purpose
Write formatted output to an output stream.
Prototype
Int16 Siofprintf (FILE *fs, const Char *formatP, ...)
Parameters
-> fs | An output stream to which to write the formatted output. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> ... | Zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings). Returns a negative number if there is an error.
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported.
See Also
fprintf
Siofputc

Purpose
Write a character to the output stream.
Prototype
Int16 Siofputc (Int16 c, FILE *fs)
Parameters
-> c | A character to write to the output stream. |
-> fs | An output stream to which to write the character. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
Result
The character that was written. If an error occurs, the value EOF is returned.
See Also
fputc
Siofputs

Purpose
Write a string to the output stream.
Prototype
Int16 Siofputs (const Char *strP, FILE *fs)
Parameters
-> strP | A pointer to the string to write. |
-> fs | An output stream to which to write the string. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
Result
Returns 0 on success and the value EOF on error.
See Also
fputs
Siogets

Purpose
Read a string from the stdin input stream.
Prototype
Char *Siogets (Char *strP)
Parameters
<- strP | A pointer to the returned string. |
Result
A pointer to the string read from the input stream. If an error or EOF occurs before any characters are read, returns NULL.
Comments
The returned string does not include a null terminator. You must ensure that the input line, if any, is sufficiently short to fit in the string.
See Also
gets
Sioprintf

Purpose
Write formatted output to the stdout output stream.
Prototype
Int16 Sioprintf (const Char *formatP, ...)
Parameters
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> ... | Zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings).
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported. Returns a negative number if there is an error.
See Also
printf
Sioputs

Purpose
Write a string to the output stream stdout.
Prototype
Int16 Sioputs (const Char *strP)
Parameters
-> strP | A pointer to the string to write to stdout. |
Result
Returns a nonnegative value on success and the value EOF on error.
See Also
puts
Siosystem

Purpose
Execute another Stdio command.
Prototype
Int16 Siosystem (const Char *cmdStrP)
Parameters
-> cmdStrP | A pointer to a string containing the command line to execute. |
Result
Returns a value >= 0 on success or < 0 on failure.
Comments
This function first looks for a built-in command with the specified name. If none is found, it looks for a Stdio application database with the name "Cmd-cmdname" where cmdname is the first word in the command string cmdStrP.
See Also
SioExecCommand, system
Siovfprintf

Purpose
Write formatted output to the stdout output stream.
Prototype
Int16 Siovfprintf (FILE *fs, const Char *formatP, _Palm_va_list args)
Parameters
-> fs | An output stream to which to write the formatted output. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> args | A pointer to a list of zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings). Returns a negative number if there is an error.
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported.
See Also
vfprintf
sprintf

Purpose
Macro that calls StrPrintF to write formatted output to the stdout output stream.
Prototype
sprintf (formatP, ...)
Parameters
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> ... | Zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings).
Comments
See StrVPrintF for details on which format specifications are supported. Returns a negative number if there is an error.
system

Purpose
Macro that calls Siosystem to execute another Stdio command.
Prototype
system (cmdStrP)
Parameters
-> cmdStrP | A pointer to a string containing the command line to execute. |
Result
Returns a value >= 0 on success or < 0 on failure.
Comments
This function first looks for a built-in command with the specified name. If none is found, it looks for a Stdio application database with the name "Cmd-cmdname" where cmdname is the first word in the command string cmdStrP.
See Also
SioExecCommand
vfprintf

Purpose
Macro that calls Siovfprintf to write formatted output to the stdout output stream.
Prototype
vfprintf (fs, formatP, args)
Parameters
-> fs | An output stream to which to write the formatted output. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> args | A pointer to a list of zero or more parameters to be formatted as specified by the formatP string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings). Returns a negative number if there is an error.
Comments
This function internally calls StrVPrintF to do the formatting. See that function for details on which format specifications are supported.
vsprintf

Purpose
Macro that calls StrVPrintF to write formatted output to the stdout output stream.
Prototype
vsprintf (fs, formatP, args)
Parameters
-> fs | An output stream to which to write the formatted output. You can specify only the value stdout for this parameter; alternate streams are not currently implemented. |
-> formatP | A pointer to a format string that controls how subsequent arguments are converted for output. |
-> args | A pointer to a list of zero or more parameters to be formatted as specified by the y string. |
Result
Returns the number of characters written out (not including the null terminator used to end output strings). Returns a negative number if there is an error.
Comments
See StrVPrintF for details on which format specifications are supported.
Standard IO Provider Functions

These functions are used by a standard IO provider application.
SioClearScreen

Purpose
Clears the entire standard IO output field.
Prototype
void SioClearScreen (void)
Parameters
Result
Returns nothing.
SioExecCommand

Purpose
Executes a command line.
Prototype
Int16 SioExecCommand (const Char *cmd)
Parameters
-> cmd | A pointer to a string containing the command line to execute. |
Result
Returns a value >= 0 on success or < 0 on failure.
Comments
This function first looks for a built-in command with the specified name. If none is found, it looks for a Stdio application database with the name "Cmd-cmdname" where cmdname is the first word in the command string cmd.
If you pass the string "help" or "?" for the cmd parameter, SioExecCommand causes a help string to be printed for each built-in command. It actually executes each built-in command, passing the string "?" as argv[1]. Each command should handle this argument by printing a help line.
The SioExecCommand function is faster than calling system to execute a command. However, SioExecCommand can be called only by the standard IO provider application, not the standard IO application.
SioFree

Purpose
Closes down the standard IO manager.
Prototype
Err SioFree (void)
Parameters
Result
Returns 0 on success.
SioHandleEvent

Purpose
Handles an event in the form that contains the standard IO output field and scroll arrows if the event belongs to the text field or scroll arrows.
Prototype
Boolean SioHandleEvent (SysEventType *event)
Parameters
-> event | Pointer to an EventType structure. |
Result
Returns true if the event was handled and should not be processed by the application's own form event handler; returns false otherwise.
Comments
This function must be called from the form event handler before it does its own processing with any of the objects unrelated to standard IO in the form.
SioInit

Purpose
Initializes the standard IO manager.
Prototype
Err SioInit (UInt16 formID, UInt16 fieldID, UInt16 scrollerID)
Parameters
-> formID | The ID of the form that contains the input/output field. |
-> fieldID | The ID of the field to be used for input/output. |
-> scrollerID | The ID of the scroller associated with the input/output form. |
Result
Returns 0 on success.
Application-Defined Function

You must supply this function in your stdio application.
SioMain

Purpose
The main entry point for the stdio application.
Prototype
Int16 SioMain (UInt16 argc, const Char *argv[])
Parameters
-> argc | The number of parameters passed on the command line. |
-> argv | An array of character pointers, one for each parameter passed on the command line. |
Result
The return value from this routine is passed back to the system call that invoked it. Return 0 for no error.
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