SCANF(3S)																 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, 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 `', which will be added.  The input field is terminated by a space character or a new-
	   line.

       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   a floating point number is expected; the next field is converted accordingly and  stored  through  the  corresponding  argument,  which
       f   should be a pointer to a float.  The input format for floating point numbers is an optionally signed string of digits possibly contain-
	   ing 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 or f 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'.  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' 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.

7th Edition							   May 15, 1985 							 SCANF(3S)