# 2.11BSD#431 - /usr/man/cat3/fscanf.0

    SCANF(3S)	    UNIX Programmer's Manual		SCANF(3S)

    NAME
         scanf, fscanf, sscanf - formatted input conversion

    SYNOPSIS
         #include <stdio.h>

         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, 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 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:

    Printed 11/26/99	  May 15, 1985				1

    SCANF(3S)	    UNIX Programmer's Manual		SCANF(3S)

         %	 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.

         e
    	  f
    	       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 or f may be capitalized or preceded by l to
         indicate a pointer to double rather than to float.  The

    Printed 11/26/99	  May 15, 1985				2

    SCANF(3S)	    UNIX Programmer's Manual		SCANF(3S)

         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.

    Printed 11/26/99	  May 15, 1985				3

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