.\" @(#)printf.3 6.5 (Berkeley) %G%
.TH PRINTF 3S "October 22, 1987"
printf, fprintf, sprintf \- formatted output conversion
.B fprintf(stream, format
.B vfprintf(stream, format, args)
.B vsprintf(s, format, args)
places output on the standard output stream
places output on the named output
places `output' in the string
followed by the character `\\0'.
Alternate forms, in which the arguments have already been
captured using the variable-length argument facilities of
are available under the names
Each of these functions converts, formats, and prints its arguments after
the first under control of the first argument.
The first argument is a character string which contains two types of objects:
plain characters, which are simply copied to the output stream,
and conversion specifications, each of which causes conversion and printing
Each conversion specification is introduced by the character
The remainder of the conversion specification includes
Zero or more of the following flags:
specifying that the value should be converted to an ``alternate form''.
conversions, this option has no effect. For
conversions, the precision of the number is increased to force the first
character of the output string to a zero. For
conversion, a non-zero result has the string
conversions, the result will always contain a decimal point, even if no
digits follow the point (normally, a decimal point only appears in the
results of those conversions if a digit follows the decimal point). For
conversions, trailing zeros are not removed from the result as they
a minus sign `\-' which specifies
of the converted value in the indicated field;
a `+' character specifying that there should always be
a sign placed before the number when using signed conversions;
a space specifying that a blank should be left before a positive number
during a signed conversion. A `+' overrides a space if both are used;
a zero `0' character indicating that zero-padding should be used
rather than blank-padding. A `\-' overrides a `0' if both are used;
an optional digit string specifying a
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
(note that a leading zero is a flag,
but an embedded zero is part of a field width);
an optional period, followed by
an optional digit string giving a
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; if the digit string is missing,
the precision is treated as zero;
specifying that a following
corresponds to a long integer
corresponds to a pointer to a long integer
specifying that a following
corresponds to a short integer
corresponds to a pointer to a short integer
a character which indicates the type of
conversion to be applied.
A field width or precision may be `*' instead of a digit string.
the field width or precision.
The conversion characters
is converted to signed decimal, unsigned octal, or
unsigned hexadecimal notation respectively.
is converted to decimal notation
in the style `[\fB\-\fR]ddd.ddd'
where the number of d's after the decimal point
is equal to the precision specification
if the precision is explicitly 0, no digits and
no decimal point are printed.
is converted in the style
`[\fB\-\fR]d\fB.\fRddd\fBe\fR\(+-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,
An uppercase E is used for `E' conversion.
whichever gives full precision in minimum space.
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.
and printed (the result will be in the
range 0 through MAXUINT, where MAXUINT equals 4294967295 on a VAX-11
is taken to be a pointer to an integer (possibly
through which is stored the number of characters written
to the output stream (or string) so far by this call to
is taken to be a pointer to
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.
the number of characters printed, or -1 if an error occurred.
To print a date and time in the form `Sunday, July 3, 10:02',
are pointers to null-terminated strings:
printf("%s, %s %d, %02d:%02d", weekday, month, day, hour, min);
printf("pi = %.5f", 4*atan(1.0));
The functions still supports \fI%D\fP, \fI%O\fP, and \fI%U\fP. Do not
use these formats, as they will be disappearing soon.
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