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 3/13/89 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.
Printed 3/13/89 2
PRINTF(3S) COMMAND REFERENCE PRINTF(3S)
c The character arg is printed.
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
errors which cause a type mismatch may induce fatal runtime
errors. Also, very wide specifier fields (>128 characters)
fail.
SEE ALSO
putc(3s), scanf(3s), and ecvt(3c).
Printed 3/13/89 3
%%index%%
na:312,106;
sy:418,1908;
de:2326,2149;4859,2786;8029,968;
ex:8997,440;
ca:9437,343;
se:9780,169;
%%index%%000000000130