PRINTF(3S) COMMAND REFERENCE PRINTF(3S)
NAME
printf, fprintf, sprintf - formatted output conversion
SYNOPSIS
#include <stdio.h>
int printf(format [ , arg ] ... )
char *format;
int fprintf(stream, format [ , arg ] ... )
FILE *stream;
char *format;
char *sprintf(s, format [ , arg ] ... )
char *s, format;
DESCRIPTION
Printf places output on the standard output stream stdout.
The return value is 0 unless an error occurred, in which
case EOF is returned.
Fprintf places output on the named output stream. The
return value is 0 unless an error occurred, in which case
EOF is returned.
Sprintf places output in the string s, followed by the
character \0. The return value is a pointer to the string
s.
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
of the next successive arg printf.
Each conversion specification is introduced by the character
%. Following the %, there may be, in this order
- An optional minus sign (-) which specifies left adjustment
of the converted value in the indicated field.
- 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.
- An optional dot (.) which serves to separate the field
width from the next digit string.
Printed 10/17/86 1
PRINTF(3S) COMMAND REFERENCE PRINTF(3S)
- An optional digit string specifying 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
- An optional # character specifying that the value should
be converted to an alternate form. For c, d, s, and u
conversions, this option has no effect. For o conversions,
the precision of the number is increased to force the first
character of the output string to a zero. For x(X)
conversion, a nonzero result has the string 0x(0X) prepended
to it. For e, E, f, g, and G 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 g and G conversions, trailing zeros are not removed from
the result as they would otherwise be.
- The character l specifying that a following d, o, x, or u
corresponds to a long integer arg.
- 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 decimal, octal, or
hexadecimal notation respectively.
f The float or double arg is converted to decimal
notation 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, six digits are given; if the precision is
explicitly 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
precision specification for the argument; when the
precision is missing, six 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.
Printed 10/17/86 2
PRINTF(3S) COMMAND REFERENCE 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
MAXUINT, where MAXUINT equals 4294967295).
% Print a %; no argument is converted.
In no case does a nonexistent 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 by putc(3s).
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 five decimals:
printf("pi = %.5f", 4*atan(1.0));
CAVEATS
It is up the the programmer to ensure that the parameters
passed to printf match the format string. Programming er-
rors which cause a type mismatch may induce fatal runtime
errors. Also, very wide specifier fields (>128 characters)
fail.
SEE ALSO
putc(3s), scanf(3s), ecvt(3c).
Printed 10/17/86 3
%%index%%
na:72,90;
sy:162,1244;
de:1406,1935;3485,2685;6314,903;
ex:7217,423;
ca:7640,317;
se:7957,138;
%%index%%000000000128