.TH PRINTN 3F
.UC
.SH NAME
printn, fprntn, sprntn \- formatted output conversion
.SH SYNTAX
.B character*(L) format
.br
.B call printn(format
.RB [ ,
arg ] ...
.B )
.PP
.B integer fileid
.br
.B character*(L) format
.br
.B call fprntn(fileid, format
.RB [ ,
arg ] ...
.B )
.SM
.PP
.B character*(L) s, sprntn, format
.br
.B s = sprntn(format
.RB [ ,
arg ] ...
.B )
.SH DESCRIPTION
.I Printn
places output on the standard output.
.I Fprntn
places output on the 
file associated with
.I fileid
(see
.IR open (3F)).
.I Sprntn
returns `output' as its function value.
.PP
Each of these functions 
converts, formats, and prints its arguments after the
.I format
under control of the
.I format
argument.
The
.I format
argument is a character string
which contains
two types of objects:
plain characters, which are simply copied to the
output,
and conversion specifications,
each of which causes conversion and printing
of the next successive
argument.
.PP
Each conversion specification is introduced by
the character
.BR % .
Following the
.BR % ,
there may be:
.TP
\-
an optional minus sign `\-' which specifies
.I "left adjustment"
of the converted value
in the
indicated field;
.TP
\-
an optional digit string
.B m ,
specifying a
.I "field width,"
.I "iteration count,"
or
.I "array size;"
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;
.TP
\-
an optional period
.RB ` . '
which serves to
separate the field width from the
next digit string;
.TP
\-
an optional digit string
specifying a
.I 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;
.TP
\-
the character
.B l
specifying that a following
.BR d ,
.BR o ,
or
.BR x ,
corresponds to an
.B integer*4
.I argument.
(A capitalized conversion code accomplishes
the same thing.)
.TP
\-
a character which indicates the type of
conversion to be applied.
.PP
A field width or precision may be `*'
and an iteration count
or array size
may be `^'
instead of a digit string.
In these cases an
.B integer*2
.I arg
supplies
the value used.
.PP
The conversion characters
and their meanings are
.TP
.B dox
The integer
.I arg
is converted to decimal, octal, or
hexadecimal notation respectively.
.TP
.B n
(Equivalent to
.BR 'ld' ).
The
.B integer*4
.I arg
is converted to decimal notation.
.TP
.B f
The
.B real
or
.B double
.B precision
.I arg
is converted to decimal notation
in the style `[\fB\-\fP]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 explicitly 0, no digits and
no decimal point are printed.
.TP
.B e
The
.B real
or
.B double
.B precision
.I arg
is converted in the style
`[\fB\-\fP]d\fB.\fPddd\fBe\fP\(+-dd'
where there is one digit before the decimal point and
the number after is equal to the
precision specification for the argument;
when the precision is missing,
6 digits are produced.
.TP
.B g
The
.B real
or
.B double precision
.I arg
is printed in style
.BR d ,
in style
.BR f ,
or in
style
.BR e ,
whichever gives full precision in minimum space.
.TP
.B c
The character
.I arg
is printed.
Null characters are ignored.
.TP
.B s
.I arg
is taken to be a string
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.
.TP
.B a
Take the next argument to be an array
of dimension
.BR m .
No argument is converted.
.TP
.B (
Begin loop:
.B n
is used as the number
of iterations.
If
.B m
is omitted,
the last
.B m
is used.
No argument is converted.
.TP
.B {
Begin loop and take the
next argument to be an array.
.RB '% m {'
is equivalent to
.RB '% m a% m ('.
.B m
is used as both the iteration count
and the array dimension.
No argument is converted.
.TP
.B )
End of loop.
No argument is converted.
.TP
.B }
Same as ')'.
.TP
.B %
Print a `%'; no argument is converted.
.PP
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
.I printn
are printed by 
.IR putc (3F).
.SH EXAMPLES
To print a date and time in the form `Sunday, July 3, 10:02',
where
.I weekday
and
.I month
are null-terminated strings:
.RS
.HP
.nh
printn('%s, %s %d, %02d:%02d', weekday, month, day, hour, min);
.RE
.hy
.PP
To print
.if n pi
.if t \(*p
to 5 decimals:
.IP
printn('pi = %.5f', 4*atan(1.0));
.SH "SEE ALSO"
putc(3F),
scann(3F)
.SH BUGS
Very wide fields (>128 characters) fail.
.SH AUTHOR
James Herriot and Bruce Julian, U.S. Geological Survey, Menlo Park, 
California