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SCANF(3S)                                                            SCANF(3S)



NAME
       scanf, fscanf, sscanf - formatted input conversion

SYNOPSIS
       #include <&lt;stdio.h>&gt;

       scanf(format [ , pointer ] . . .  )
       char *format;

       fscanf(stream, format [ , pointer ] . . .  )
       FILE *stream;
       char *format;

       sscanf(s, format [ , pointer ] . . .  )
       char *s, *format;

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, interprets 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 control string usually contains  conversion  specifications,  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 corre-
       sponding 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 specified, 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 characters are legal:

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

       d   a decimal integer is expected; the corresponding argument 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 argument 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  sup-
           pressed  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.

       e   a floating point number is expected; the next  field  is  converted
       f   accordingly  and  stored  through the corresponding 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 characters.  The
           left bracket is followed  by  a  set  of  characters  and  a  right
           bracket;  the characters between the brackets define a set of char-
           acters making up the string.  If the first character is not circum-
           flex (^), the input field is all characters until the first charac-
           ter 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  charac-
           ters  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 argu-
       ment list.  Similarly, the conversion characters e or f may be capital-
       ized  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(3S), printf(3S)

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.



                                19 January 1983                      SCANF(3S)