NAME

     scanf, fscanf, sscanf, vscanf, vfscanf, vsscanf -  formatted
     input conversion


SYNOPSIS

     #include <stdio.h>
     #include <stdarg.h>

     int scanf(const char *format [, pointer] ...)
     int fscanf(FILE *stream, const char *format [, pointer] ...)
     int sscanf(const char *s, const char *format [, pointer] ...)
     int vscanf(const char *format, va_list args)
     int vfscanf(FILE *stream, const char *format, va_list args)
     int vsscanf(const char *s, const char *format, va_list args)


DESCRIPTION

     Scanf reads from the standard input  stream  stdin.   Fscanf
     reads  from  the  named input stream.  Sscanf reads from the
     character string s.  Each function reads characters,  inter-
     prets  them according to a format, and stores the results in
     its arguments.  Each expects as arguments a  control  string
     format,  described  below,  and  a  set of pointer arguments
     indicating where the converted input should be stored.

     The v*scanf functions can be used to make functions like the
     first  three  by  using  the stdarg(3) method to process the
     argument pointers.

     The control string usually  contains  conversion  specifica-
     tions,  which  are  used  to  direct interpretation of input
     sequences.  The control string may contain:

     1.  Blanks, tabs or newlines,  which  match  optional  white
         space in the input.

     2.  An ordinary character (not %) which must match the  next
         character of the input stream.

     3.  Conversion specifications, consisting of  the  character
         %,  an  optional  assignment suppressing character *, an
         optional numerical maximum field width, and a conversion
         character.

     A conversion specification directs  the  conversion  of  the
     next  input  field;  the  result  is  placed in the variable
     pointed to by the corresponding argument, unless  assignment
     suppression  was  indicated by *.  An input field is defined
     as a string of non-space characters; it extends to the  next
     inappropriate  character or until the field width, if speci-
     fied, is exhausted.


     The conversion character indicates the interpretation of the
     input field; the corresponding pointer argument must usually
     be of a restricted type.  The following  conversion  charac-
     ters are legal:

     %   a single `%' is expected in the input at this point;  no
         assignment is done.

     d   a decimal integer is expected; the  corresponding  argu-
         ment should be an integer pointer.

     o   an octal integer is expected; the corresponding argument
         should be a integer pointer.

     x   a hexadecimal integer  is  expected;  the  corresponding
         argument should be an integer pointer.

     s   a character string is expected; the corresponding  argu-
         ment  should be a character pointer pointing to an array
         of characters large enough to accept the  string  and  a
         terminating  `\0', which will be added.  The input field
         is terminated by a space character or a newline.

     c   a character  is  expected;  the  corresponding  argument
         should  be  a  character  pointer.  The normal skip over
         space characters is suppressed in this case; to read the
         next  non-space  character, try `%1s'.  If a field width
         is given, the corresponding argument should refer  to  a
         character  array, and the indicated number of characters
         is read.

     efg a floating point number is expected; the next  field  is
         converted accordingly and stored through the correspond-
         ing argument, which should be a pointer to a float.  The
         input format for floating point numbers is an optionally
         signed string of digits possibly  containing  a  decimal
         point, followed by an optional exponent field consisting
         of an E or e followed by an optionally signed integer.

     [   indicates a string not to be delimited by space  charac-
         ters.   The left bracket is followed by a set of charac-
         ters and a right bracket;  the  characters  between  the
         brackets  define  a  set  of  characters  making  up the
         string.  If the first character is not  circumflex  (^),
         the  input field is all characters until the first char-
         acter not in the set between the brackets; if the  first
         character  after  the left bracket is ^, the input field
         is all characters until the first character which is  in
         the  remaining  set  of characters between the brackets.
         The corresponding argument must  point  to  a  character
         array.

     The conversion characters d, o and x may be  capitalized  or
     preceded by l to indicate that a pointer to long rather than
     to int is in the argument list.  Similarly,  the  conversion
     characters  e, f or g may be capitalized or preceded by l to
     indicate a pointer to double  rather  than  to  float.   The
     conversion  characters  d,  o  and x may be preceded by h to
     indicate a pointer to short rather than to int.

     The  scanf  functions  return  the  number  of  successfully
     matched  and  assigned  input  items.   This  can be used to
     decide how many input items were found.  The constant EOF is
     returned upon end of input; note that this is different from
     0, which means that no conversion was  done;  if  conversion
     was  intended, it was frustrated by an inappropriate charac-
     ter in the input.

     For example, the call

               int i; float x; char name[50];
               scanf("%d%f%s", &i, &x, name);

     with the input line

          25   54.32E-1  thompson

     will assign to i the value 25, x the value 5.432,  and  name
     will contain `thompson\0' .  Or,

          int i; float x; char name[50];
          scanf("%2d%f%*d%[1234567890]", &i, &x, name);

     with input

          56789 0123 56a72

     will assign 56 to i, 789.0 to x, skip `0123', and place  the
     string `56\0' in name.  The next call to getchar will return
     `a'.


SEE ALSO

     atof(3), getc(3), printf(3), stdarg(3).


DIAGNOSTICS

     The scanf functions return EOF on end of input, and a  short
     count for missing or illegal data items.


BUGS

     The success of literal matches and suppressed assignments is
     not directly determinable.