* positioning function (fseek, fsetpos, or rewind), and input be not be
    * directly followed by output without an intervening call to the fflush
    * fuction or to a file positioning function, unless the input operation
    * encounters end-of-file. Opening a file with update mode may open or
    * create a binary stream in some implementations (but not under RISCOS/
    * Arthur/Brazil). When opened, a stream is fully buffered if and only if
    * it does not refer to an interactive device. The error and end-of-file
    * indicators for the stream are cleared.
    * Returns: a pointer to the object controlling the stream. If the open
    *          operation fails, fopen returns a null pointer.
    */
extern FILE *freopen(const char * /*filename*/, const char * /*mode*/,
                     FILE * /*stream*/);
   /*
    * opens the file whose name is the string pointed to by filename and
    * associates the stream pointed to by stream with it. The mode argument is
    * used just as in the fopen function.
    * The freopen function first attempts to close any file that is associated
    * with the specified stream. Failure to close the file successfully is
    * ignored. The error and end-of-file indicators for the stream are cleared.
    * Returns: a null pointer if the operation fails. Otherwise, freopen
    *          returns the value of the stream.
    */
extern void setbuf(FILE * /*stream*/, char * /*buf*/);
   /*
    * Except that it returns no value, the setbuf function is equivalent to the
    * setvbuf function invoked with the values _IOFBF for mode and BUFSIZ for
    * size, or (if buf is a null pointer), with the value _IONBF for mode.
    * Returns: no value.
    */
extern int setvbuf(FILE * /*stream*/, char * /*buf*/,
                   int /*mode*/, size_t /*size*/);
   /*
    * may be used after the stream pointed to by stream has been associated
    * with an open file but before it is read or written. The argument mode
    * determines how stream will be buffered, as follows: _IOFBF causes
    * input/output to be fully buffered; _IOLBF causes output to be line
    * buffered (the buffer will be flushed when a new-line character is
    * written, when the buffer is full, or when input is requested); _IONBF
    * causes input/output to be completely unbuffered. If buf is not the null
    * pointer, the array it points to may be used instead of an automatically
    * allocated buffer (the buffer must have a lifetime at least as great as
    * the open stream, so the stream should be closed before a buffer that has
    * automatic storage duration is deallocated upon block exit). The argument
    * size specifies the size of the array. The contents of the array at any
    * time are indeterminate.
    * Returns: zero on success, or nonzero if an invalid value is given for
    *          mode or size, or if the request cannot be honoured.
    */

#pragma -v1   /* hint to the compiler to check f/s/printf format */
extern int fprintf(FILE * /*stream*/, const char * /*format*/, ...);
   /*
    * writes output to the stream pointed to by stream, under control of the
    * string pointed to by format that specifies how subsequent arguments are
    * converted for output. If there are insufficient arguments for the format,
    * the behaviour is undefined. If the format is exhausted while arguments
    * remain, the excess arguments are evaluated but otherwise ignored. The
    * fprintf function returns when the end of the format string is reached.
    * The format shall be a multibyte character sequence, beginning and ending
    * in its initial shift state. The format is composed of zero or more
    * directives: ordinary multibyte characters (not %), which are copied
    * unchanged to the output stream; and conversion specifiers, each of which
    * results in fetching zero or more subsequent arguments. Each conversion
    * specification is introduced by the character %. For a description of the
    * available conversion specifiers refer to section 4.9.6.1 in the ANSI
    * draft mentioned at the start of this file or to any modern textbook on C.
    * The minimum value for the maximum number of characters producable by any
    * single conversion is at least 509.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
extern int printf(const char * /*format*/, ...);
   /*
    * is equivalent to fprintf with the argument stdout interposed before the
    * arguments to printf.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
extern int sprintf(char * /*s*/, const char * /*format*/, ...);
   /*
    * is equivalent to fprintf, except that the argument s specifies an array
    * into which the generated output is to be written, rather than to a
    * stream. A null character is written at the end of the characters written;
    * it is not counted as part of the returned sum.
    * Returns: the number of characters written to the array, not counting the
    *          terminating null character.
    */
#pragma -v2   /* hint to the compiler to check f/s/scanf format */
extern int fscanf(FILE * /*stream*/, const char * /*format*/, ...);
   /*
    * reads input from the stream pointed to by stream, under control of the
    * string pointed to by format that specifies the admissible input sequences
    * and how thay are to be converted for assignment, using subsequent
    * arguments as pointers to the objects to receive the converted input. If
    * there are insufficient arguments for the format, the behaviour is
    * undefined. If the format is exhausted while arguments remain, the excess
    * arguments are evaluated but otherwise ignored.
    * The format is composed of zero or more directives: one or more
    * white-space characters; an ordinary character (not %); or a conversion
    * specification. Each conversion specification is introduced by the
    * character %. For a description of the available conversion specifiers
    * refer to section 4.9.6.2 in the ANSI draft mentioned at the start of this
    * file, or to any modern textbook on C.
    * If end-of-file is encountered during input, conversion is terminated. If
    * end-of-file occurs before any characters matching the current directive
    * have been read (other than leading white space, where permitted),
    * execution of the current directive terminates with an input failure;
    * otherwise, unless execution of the current directive is terminated with a
    * matching failure, execution of the following directive (if any) is
    * terminated with an input failure.
    * If conversions terminates on a conflicting input character, the offending
    * input character is left unread in the input strem. Trailing white space
    * (including new-line characters) is left unread unless matched by a
    * directive. The success of literal matches and suppressed asignments is
    * not directly determinable other than via the %n directive.
    * Returns: the value of the macro EOF if an input failure occurs before any
    *          conversion. Otherwise, the fscanf function returns the number of
    *          input items assigned, which can be fewer than provided for, or
    *          even zero, in the event of an early conflict between an input
    *          character and the format.
    */
extern int scanf(const char * /*format*/, ...);
   /*
    * is equivalent to fscanf with the argument stdin interposed before the
    * arguments to scanf.
    * Returns: the value of the macro EOF if an input failure occurs before any
    *          conversion. Otherwise, the scanf function returns the number of
    *          input items assigned, which can be fewer than provided for, or
    *          even zero, in the event of an early matching failure.
    */
extern int sscanf(const char * /*s*/, const char * /*format*/, ...);
   /*
    * is equivalent to fscanf except that the argument s specifies a string
    * from which the input is to be obtained, rather than from a stream.
    * Reaching the end of the string is equivalent to encountering end-of-file
    * for the fscanf function.
    * Returns: the value of the macro EOF if an input failure occurs before any
    *          conversion. Otherwise, the scanf function returns the number of
    *          input items assigned, which can be fewer than provided for, or
    *          even zero, in the event of an early matching failure.
    */
#pragma -v0   /* back to default */
extern int vprintf(const char * /*format*/, __va_list /*arg*/);
   /*
    * is equivalent to printf, with the variable argument list replaced by arg,
    * which has been initialised by the va_start macro (and possibly subsequent
    * va_arg calls). The vprintf function does not invoke the va_end function.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
extern int vfprintf(FILE * /*stream*/,
                   const char * /*format*/, __va_list /*arg*/);
   /*
    * is equivalent to fprintf, with the variable argument list replaced by
    * arg, which has been initialised by the va_start macro (and possibly
    * subsequent va_arg calls). The vfprintf function does not invoke the
    * va_end function.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
extern int vsprintf(char * /*s*/, const char * /*format*/, __va_list /*arg*/);
   /*
    * is equivalent to sprintf, with the variable argument list replaced by
    * arg, which has been initialised by the va_start macro (and possibly
    * subsequent va_arg calls). The vsprintf function does not invoke the
    * va_end function.
    * Returns: the number of characters written in the array, not counting the
    *          terminating null character.
    */

extern int fgetc(FILE * /*stream*/);
   /*
    * obtains the next character (if present) as an unsigned char converted to
    * an int, from the input stream pointed to by stream, and advances the
    * associated file position indicator (if defined).
    * Returns: the next character from the input stream pointed to by stream.
    *          If the stream is at end-of-file, the end-of-file indicator is
    *          set and fgetc returns EOF. If a read error occurs, the error
    *          indicator is set and fgetc returns EOF.
    */
extern char *fgets(char * /*s*/, int /*n*/, FILE * /*stream*/);
   /*
    * reads at most one less than the number of characters specified by n from
    * the stream pointed to by stream into the array pointed to by s. No
    * additional characters are read after a new-line character (which is
    * retained) or after end-of-file. A null character is written immediately
    * after the last character read into the array.
    * Returns: s if successful. If end-of-file is encountered and no characters
    *          have been read into the array, the contents of the array remain
    *          unchanged and a null pointer is returned. If a read error occurs
    *          during the operation, the array contents are indeterminate and a
    *          null pointer is returned.
    */
extern int fputc(int /*c*/, FILE * /*stream*/);
   /*
    * writes the character specified by c (converted to an unsigned char) to
    * the output stream pointed to by stream, at the position indicated by the
    * asociated file position indicator (if defined), and advances the
    * indicator appropriately. If the file position indicator is not defined,
    * the character is appended to the output stream.
    * Returns: the character written. If a write error occurs, the error
    *          indicator is set and fputc returns EOF.
    */
extern int fputs(const char * /*s*/, FILE * /*stream*/);
   /*
    * writes the string pointed to by s to the stream pointed to by stream.
    * The terminating null character is not written.
    * Returns: EOF if a write error occurs; otherwise it returns a nonnegative
    *          value.
    */
extern int getc(FILE * /*stream*/);