printf(3BSD) (BSD System Compatibility) printf(3BSD)
NAME
printf: sprintf, vsprintf - (BSD) formatted output conversion
SYNOPSIS
/usr/ucb/cc [flag . . . ] file . . .
#include <stdio.h>
char *sprintf(char *s, char *format [ , arg ] ... );
char *vsprintf(char *s, char *format, va_list ap);
DESCRIPTION
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.
vsprintf is the same as sprintf except that instead of being
called with a variable number of arguments, it is called with
an argument list as defined by varargs(5).
Each of these functions converts, formats, and prints its args
under control of the format. The format is a character string
that 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 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
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printf(3BSD) (BSD System Compatibility) printf(3BSD)
significant digits for the g and G conversion, 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 shows the type of conversion to be
applied.
A field width or precision or both may be 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 converted. 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
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printf(3BSD) (BSD System Compatibility) printf(3BSD)
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 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 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 for 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
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printf(3BSD) (BSD System Compatibility) printf(3BSD)
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
character (\0) is encountered or until the number of
characters shown 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.
A non-existent or small field width does not 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 field width. Characters generated by
printf and fprintf are printed as if putc(3S) had been called.
Return Values
sprintf and vsprintf always return s.
REFERENCES
econvert(3BSD), fprintf(3S), fscanf(3S), putc(3S), varargs(5)
NOTICES
Fields greater than 128 characters fail.
Copyright 1994 Novell, Inc. Page 4