printf(3UCB) SunOS/BSD Compatibility Library Functions printf(3UCB)NAME
printf, fprintf, sprintf, vprintf, vfprintf, vsprintf - formatted out‐
put conversion
SYNOPSIS
/usr/ucb/cc [flag ...] file ...
#include <stdio.h>
int printf(format, ...)
const char *format;
int fprintf(stream, format, va_list)
FILE *stream;
char *format;
va_dcl;
char *sprintf(s, format, va_list)
char *s, *format;
va_dcl;
int vprintf(format, ap)
char *format;
va_list ap;
int vfprintf(stream, format, ap)
FILE *stream;
char *format;
va_list ap;
char *vsprintf(s, format, ap)
char *s, *format;
va_list ap;
DESCRIPTIONprintf() places output on the standard output stream stdout. fprintf()
places output on the named output stream. sprintf() places "output,"
followed by the NULL character (\0), in consecutive bytes starting at
*s; it is the user's responsibility to ensure that enough storage is
available.
vprintf(), vfprintf(), and vsprintf() are the same as printf(),
fprintf(), and sprintf() respectively, except that instead of being
called with a variable number of arguments, they are called with an
argument list as defined by <varargs.h>.
Each of these functions converts, formats, and prints its args under
control of the format. The format 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 con‐
version and printing of zero or more args. The results are undefined if
there are insufficient args for the format. If the format is exhausted
while args remain, the excess args are simply ignored.
Each conversion specification is introduced by the character %. After
the %, the following appear in sequence:
o Zero or more flags, which modify the meaning of the conver‐
sion specification.
o An optional decimal digit string specifying a minimum field
width. If the converted value has fewer characters than the
field width, it will be padded on the left (or right, if the
left-adjustment flag `−', described below, has been given)
to the field width. The padding is with blanks unless the
field width digit string starts with a zero, in which case
the padding is with zeros.
o A precision that gives the minimum number of digits to
appear for the d, i, o, u, x, or X conversions, the number
of digits to appear after the decimal point for the e, E,
and f conversions, the maximum number of significant digits
for the g and G conversion, or the maximum number of charac‐
ters to be printed from a string in s conversion. The pre‐
cision takes the form of a period (.) followed by a decimal
digit string; a NULL digit string is treated as zero. Pad‐
ding specified by the precision overrides the padding speci‐
fied by the field width.
o An optional l (ell) specifying that a following d, i, o, u,
x, or X conversion character applies to a long integer arg.
An l before any other conversion character is ignored.
o A character that indicates the type of conversion to be
applied.
A field width or precision or both may be indicated by an asterisk (*)
instead of a digit string. In this case, an integer arg supplies the
field width or precision. The arg that is actually converted is not
fetched until the conversion letter is seen, so the args specifying
field width or precision must appear before the arg (if any) to be con‐
verted. A negative field width argument is taken as a `−' flag followed
by a positive field width. If the precision argument is negative, it
will be changed to zero.
The flag characters and their meanings are:
− The result of the conversion will be left-justified within the
field.
+ The result of a signed conversion will always begin with a
sign (+ or −).
blank If the first character of a signed conversion is not a sign, a
blank will be prefixed to the result. This implies that if the
blank and + flags both appear, the blank flag will be ignored.
# This flag specifies that the value is to be converted to an
"alternate form." For c, d, i, s, and u conversions, the flag
has no effect. For o conversion, it increases the precision to
force the first digit of the result to be a zero. For x or X
conversion, a non-zero result will have 0x or 0X prefixed 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 appears in the result of these con‐
versions only if a digit follows it). For g and G conversions,
trailing zeroes will not be removed from the result (which
they normally are).
The conversion characters and their meanings are:
d,i,o,u,x,X The integer arg is converted to signed decimal (d or i),
unsigned octal (o), unsigned decimal (u), or unsigned
hexadecimal notation (x and X), respectively; the let‐
ters abcdef are used for x conversion and the letters
ABCDEF for X conversion. The precision specifies the
minimum number of digits to appear; if the value being
converted can be represented in fewer digits, it will be
expanded with leading zeroes. (For compatibility with
older versions, padding with leading zeroes may alterna‐
tively be specified by prepending a zero to the field
width. This does not imply an octal value for the field
width.) The default precision is 1. The result of con‐
verting a zero value with a precision of zero is a NULL
string.
f The float or double arg is converted to decimal notation
in the style [−]ddd.ddd where the number of digits after
the decimal point is equal to the precision specifica‐
tion. If the precision is missing, 6 digits are given;
if the precision is explicitly 0, no digits and no deci‐
mal point are printed.
e,E The float or double arg is converted in the style
[−]d.ddde±ddd, where there is one digit before the deci‐
mal point and the number of digits after it is equal to
the precision; when the precision is missing, 6 digits
are produced; if the precision is zero, no decimal point
appears. The E format code will produce a number with E
instead of e introducing the exponent. The exponent
always contains at least two digits.
g,G The float or double arg is printed in style f or e (or
in style E in the case of a G format code), with the
precision specifying the number of significant digits.
The style used depends on the value converted: style e
or E will be used only if the exponent resulting from
the conversion is less than −4 or greater than the pre‐
cision. Trailing zeroes are removed from the result; a
decimal point appears only if it is followed by a digit.
The e, E f, g, and G formats print IEEE indeterminate values (infinity
or not-a-number) as "Infinity" or "NaN" respectively.
c The character arg is printed.
s The arg is taken to be a string (character pointer) and characters
from the string are printed until a NULL character (\0) is encoun‐
tered or until the number of characters indicated by the precision
specification is reached. If the precision is missing, it is taken
to be infinite, so all characters up to the first NULL character
are printed. A NULL value for arg will yield undefined results.
% Print a %; no argument is converted.
In no case does a non-existent or small field width cause truncation of
a field; if the result of a conversion is wider than the field width,
the field is simply expanded to contain the conversion result. Padding
takes place only if the specified field width exceeds the actual width.
Characters generated by printf() and fprintf() are printed as if
putc(3C) had been called.
RETURN VALUES
Upon success, printf() and fprintf() return the number of characters
transmitted, excluding the null character. vprintf() and vfprintf()
return the number of characters transmitted. sprintf() and vsprintf()
always return s. If an output error is encountered, printf(), fprint(),
vprintf(), and vfprintf() return EOF.
EXAMPLES
Example 1 Examples of the printf Command To Print a Date and Time
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 %i, %d:%.2d", weekday, month, day, hour, min);
Example 2 Examples of the printf Command To Print to Five Decimal
Places
To print to five decimal places:
printf("pi = %.5f", 4 * atan(1. 0));
SEE ALSOcc(1B), econvert(3C), putc(3C), scanf(3C), vprintf(3C)NOTES
Use of these interfaces should be restricted to only applications writ‐
ten on BSD platforms. Use of these interfaces with any of the system
libraries or in multi-thread applications is unsupported.
Very wide fields (>128 characters) fail.
SunOS 5.10 30 Oct 2007 printf(3UCB)