printf(3UCB) SunOS/BSD Compatibility Library Functions printf(3UCB)
printf, fprintf, sprintf, vprintf, vfprintf, vsprintf - formatted out‐
put conversion
/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;
printf() 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(3HEAD).
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:
· Zero or more flags, which modify the meaning of the conversion
specification.
· 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.
· 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 conver‐
sion, or the maximum number of characters to be printed from a
string in s conversion. The precision takes the form of a period
(.) followed by a decimal digit string; a NULL digit string is
treated as zero. Padding specified by the precision overrides the
padding specified by the field width.
· 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.
· 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 conver‐
sions, 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 conversions 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 letters
abcdef are used for x conversion and the letters ABCDEF
for X conversion. The precision specifies the minimum num‐
ber 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 alternatively 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 converting 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 specification.
If the precision is missing, 6 digits are given; if the
precision is explicitly 0, no digits and no decimal 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 decimal
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 preci‐
sion 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 con‐
version is less than −4 or greater than the precision.
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 char‐
acter (\0) is encountered or until the number of charac‐
ters 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.
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.
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));
econvert(3C), putc(3C), scanf(3C), vprintf(3C), varargs(3HEAD)
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 5.9 18 Feb 1993 printf(3UCB)