+.Fn scanf
+function
+reads input from the standard input stream
+.Em stdin ,
+.Fn fscanf
+reads input from the stream pointer
+.Fa stream ,
+and
+.Fn sscanf
+reads its input from the character string pointed to by
+.Fa str .
+The
+.Fn vfscanf
+function
+is analogous to
+.Xr vfprintf 3
+and reads input from the stream pointer
+.Fa stream
+using a variable argument list of pointers (see
+.Xr stdarg 3 ) .
+The
+.Fn vscanf
+function scans a variable argument list from the standard input and
+the
+.Fn vsscanf
+function scans it from a string;
+these are analogous to
+the
+.Fn vprintf
+and
+.Fn vsprintf
+functions respectively.
+Each successive
+.Em pointer
+argument must correspond properly with
+each successive conversion specifier
+(but see `suppression' below).
+All conversions are introduced by the
+.Cm %
+(percent sign) character.
+The
+.Fa format
+string
+may also contain other characters.
+White space (such as blanks, tabs, or newlines) in the
+.Fa format
+string match any amount of white space, including none, in the input.
+Everything else
+matches only itself.
+Scanning stops
+when an input character does not match such a format character.
+Scanning also stops
+when an input conversion cannot be made (see below).
+.Sh CONVERSIONS
+Following the
+.Cm %
+character introducing a conversion
+there may be a number of
+.Em flag
+characters, as follows:
+.Bl -tag -width indent
+.It Cm *
+Suppresses assignment.
+The conversion that follows occurs as usual, but no pointer is used;
+the result of the conversion is simply discarded.
+.It Cm h
+Indicates that the conversion will be one of
+.Cm dioux
+or
+.Cm n
+and the next pointer is a pointer to a
+.Em short int
+(rather than
+.Em int ) .
+.It Cm l
+Indicates either that the conversion will be one of
+.Cm dioux
+or
+.Cm n
+and the next pointer is a pointer to a
+.Em long int
+(rather than
+.Em int ) ,
+or that the conversion will be one of
+.Cm efg
+and the next pointer is a pointer to
+.Em double
+(rather than
+.Em float ) .
+.It Cm L
+Indicates that the conversion will be
+.Cm efg
+and the next pointer is a pointer to
+.Em long double .
+(This type is not implemented; the
+.Cm L
+flag is currently ignored.)
+.El
+.Pp
+In addition to these flags,
+there may be an optional maximum field width,
+expressed as a decimal integer,
+between the
+.Cm %
+and the conversion.
+If no width is given,
+a default of `infinity' is used (with one exception, below);
+otherwise at most this many characters are scanned
+in processing the conversion.
+Before conversion begins,
+most conversions skip white space;
+this white space is not counted against the field width.
+.Pp
+The following conversions are available:
+.Bl -tag -width XXXX
+.It Cm %
+Matches a literal `%'.
+That is, `%\&%' in the format string
+matches a single input `%' character.
+No conversion is done, and assignment does not occur.
+.It Cm d
+Matches an optionally signed decimal integer;
+the next pointer must be a pointer to
+.Em int .
+.It Cm D
+Equivalent to
+.Xr ld ;
+this exists only for backwards compatibility.
+.It Cm i
+Matches an optionally signed integer;
+the next pointer must be a pointer to
+.Em int .
+The integer is read in base 16 if it begins
+with
+.Ql 0x
+or
+.Ql 0X ,
+in base 8 if it begins with
+.Ql 0 ,
+and in base 10 otherwise.
+Only characters that correspond to the base are used.
+.It Cm o
+Matches an octal integer;
+the next pointer must be a pointer to
+.Em unsigned int .
+.It Cm O
+Equivalent to
+.Xr lo ;
+this exists for backwards compatibility.
+.It Cm u
+Matches an optionally signed decimal integer;
+the next pointer must be a pointer to
+.Em unsigned int .
+.It Cm x
+Matches an optionally a signed hexadecimal integer;
+the next pointer must be a pointer to
+.Em unsigned int .
+.It Cm X
+Equivalent to
+.Cm lx ;
+this violates the
+.St -ansiC ,
+but is backwards compatible with previous
+.Ux
+systems.
+.It Cm f
+Matches an optionally signed floating-point number;
+the next pointer must be a pointer to
+.Em float .
+.It Cm e
+Equivalent to
+.Cm f .
+.It Cm g
+Equivalent to
+.Cm f .
+.It Cm E
+Equivalent to
+.Cm lf ;
+this violates the
+.St -ansiC ,
+but is backwards compatible with previous
+.Ux
+systems.
+.It Cm F
+Equivalent to
+.Cm lf ;
+this exists only for backwards compatibility.
+.It Cm s
+Matches a sequence of non-white-space characters;
+the next pointer must be a pointer to
+.Em char ,
+and the array must be large enough to accept all the sequence and the
+terminating
+.Dv NUL
+character.
+The input string stops at white space
+or at the maximum field width, whichever occurs first.
+.It Cm c
+Matches a sequence of
+.Em width
+count
+characters (default 1);
+the next pointer must be a pointer to
+.Em char ,
+and there must be enough room for all the characters
+(no terminating
+.Dv NUL
+is added).
+The usual skip of leading white space is suppressed.
+To skip white space first, use an explicit space in the format.
+.It Cm \&[
+Matches a nonempty sequence of characters from the specified set
+of accepted characters;
+the next pointer must be a pointer to
+.Em char ,
+and there must be enough room for all the characters in the string,
+plus a terminating
+.Dv 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
+.Cm [
projects / unix-history / blobdiff