# scanf(3)

## 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, 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 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 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
         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
         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
             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  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 characters making  up
             the  string.  If the first character is not circumflex (^), the input
             field is all characters until the first  character  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  character
         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.