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


NAME
     printf, fprintf, sprintf, vfprintf, vsprintf - formatted
     output conversion

SYNOPSIS
     #include <stdio.h>

     char *printf(format [, arg ] ...  )
     char *format;

     char *fprintf(stream, format [, arg ] ...	)
     FILE *stream;
     char *format;

     int sprintf(s, format [, arg ] ...  )
     char *s, *format;

     #include <varargs.h>
     char *vprintf(format, args)
     char *format;
     va_list args;

     char *vfprintf(stream, format, args)
     FILE *stream;
     char *format;
     va_list args;

     int vsprintf(s, format, args)
     char *s, *format;
     va_list args;

DESCRIPTION
     Printf places output on the standard output stream stdout.
     Fprintf places output on the named output stream.	Sprintf
     places `output' in the string s, followed by the character
     `\0'.  Alternate forms, in which the arguments have already
     been captured using the variable-length argument facilities
     of varargs(3), are available under the names vprintf,
     vfprintf, and vsprintf.

     Each of these functions converts, formats, and prints its
     arguments after the first under control of the first argu-
     ment.  The first argument is a character string which con-
     tains two types of objects: plain characters, which are sim-
     ply copied to the output stream, and conversion specifica-
     tions, each of which causes conversion and printing of the
     next successive arg printf.

     Each conversion specification is introduced by the character
     %.  The remainder of the conversion specification includes
     in the following order


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


     o+	  a minus sign `-' which specifies left adjustment of the
	  converted value in the indicated field;

     o+	  an optional digit string specifying a field width; if
	  the converted value has fewer characters than the field
	  width it will be blank-padded on the left (or right, if
	  the left-adjustment indicator has been given) to make
	  up the field width; if the field width begins with a
	  zero, zero-padding will be done instead of blank-
	  padding;

     o+	  an optional period, followed by an optional digit
	  string giving a precision which specifies the number of
	  digits to appear after the decimal point, for e- and
	  f-conversion, or the maximum number of characters to be
	  printed from a string;

     o+	  the character l specifying that a following d, o, x, or
	  u corresponds to a long integer arg;

     o+	  a character which indicates the type of conversion to
	  be applied.

     A field width or precision may be `*' instead of a digit
     string.  In this case an integer arg supplies the field
     width or precision.

     The conversion characters and their meanings are

     dox  The integer arg is converted to signed decimal,
	  unsigned octal, or unsigned hexadecimal notation
	  respectively.

     f	  The float or double arg is converted to decimal nota-
	  tion in the style `[-]ddd.ddd' where the number of d's
	  after the decimal point is equal to the precision
	  specification for the argument.  If the precision is
	  missing, 6 digits are given; if the precision is expli-
	  citly 0, no digits and no decimal point are printed.

     e	  The float or double arg is converted in the style
	  `[-]d.ddde+dd' where there is one digit before the
	  decimal point and the number after is equal to the pre-
	  cision specification for the argument; when the preci-
	  sion is missing, 6 digits are produced.

     g	  The float or double arg is printed in style d, in style
	  f, or in style e, whichever gives full precision in
	  minimum space.

     c	  The character arg is printed.


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


     s	  Arg is taken to be a string (character pointer) and
	  characters from the string are printed until a null
	  character or until the number of characters indicated
	  by the precision specification is reached; however if
	  the precision is 0 or missing all characters up to a
	  null are printed.

     u	  The unsigned integer arg is converted to decimal and
	  printed (the result will be in the range 0 through MAX-
	  UINT, where MAXUINT equals 4294967295 on a VAX-11 and
	  65535 on a PDP-11).

     %	  Print a `%'; no argument is converted.

     In no case does a non-existent or small field width cause
     truncation of a field; padding takes place only if the
     specified field width exceeds the actual width.  Characters
     generated by printf are printed as by putc(3S).

RETURN VALUE
     The functions all return the number of characters printed,
     or -1 if an error occurred.

EXAMPLES
     To print a date and time in the form `Sunday, July 3,
     10:02', where weekday and month are pointers to null-
     terminated strings:

	  printf("%s, %s %d, %02d:%02d", weekday, month, day,
	       hour, min);

     To print pi to 5 decimals:

	  printf("pi = %.5f", 4*atan(1.0));

SEE ALSO
     putc(3S), scanf(3S)

BUGS
     Very wide fields (>300 characters) fail.

     Only sprintf and vsprintf return a count of characters
     transferred.

     The functions still supports %D, %O, %U and %X.  Do not use
     these formats, as they will be disappearing real soon now.


Printed 11/26/99	 August 10, 1988			3


 
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