.\" @(#)printf.3 6.4 (Berkeley) %G%
printf, fprintf, sprintf \- formatted output conversion
.B fprintf(stream, format
.B _doprnt(format, args, stream)
places output on the standard output stream
places output on the named output
places `output' in the string
followed by the character `\\0'.
All of these routines work by calling the internal
using the variable-length argument facilities of
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 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.
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;
if the field width begins with a zero,
zero-padding will be done instead of blank-padding;
which serves to separate the field width from the next digit string;
an optional digit string specifying 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;
specifying that a following
corresponds to a long 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 decimal, octal, or
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,
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
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 functions \fIprintf\fP, \fIfprintf\fP, and \fIsprintf\fP return
the number of characters printf, 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));
Very wide fields (>128 characters) fail.