format a string in the style of sprintf
format formatString [arg arg ...]
This command generates a formatted string in the same way
as the ANSI C sprintf procedure (it
uses sprintf in its implementation).
formatString indicates how to format the result,
using % conversion specifiers as in
sprintf, and the additional arguments, if any,
provide values to be substituted into the result. The
return value from format is the formatted
Details on formatting
The command operates by scanning formatString
from left to right. Each character from the format string
is appended to the result string unless it is a percent
sign. If the character is a % then it is not
copied to the result string. Instead, the characters
following the % character are treated as a
conversion specifier. The conversion specifier controls
the conversion of the next successive arg to a
particular format and the result is appended to the result
string in place of the conversion specifier. If there are
multiple conversion specifiers in the format string, then
each one controls the conversion of one additional
arg. The format command must be given
enough args to meet the needs of all of the
conversion specifiers in formatString.
Each conversion specifier may contain up to six different
parts: an XPG3 position specifier, a set of
flags, a minimum field width, a precision specifier, a
length modifier, and a conversion character. Any of these
fields may be omitted except for the conversion character.
The fields that are present must appear in the order given
above. The paragraphs below discuss each of these fields
If the % is followed by a decimal number and a $,
as in ``%2$d'', then the value to convert is not
taken from the next sequential argument. Instead, it is
taken from the argument indicated by the number, where 1
corresponds to the first arg. If the conversion
specifier requires multiple arguments because of
characters in the specifier then successive
arguments are used, starting with the argument given by the
number. This follows the XPG3 conventions for
positional specifiers. If there are any positional
specifiers in formatString then all of the
specifiers must be positional.
The second portion of a conversion specifier may contain any of the
following flag characters, in any order:
The third portion of a conversion specifier is a number
giving a minimum field width for this conversion. It is
typically used to make columns line up in tabular
printouts. If the converted argument contains fewer
characters than the minimum field width then it will be
padded so that it is as wide as the minimum field width.
Padding normally occurs by adding extra spaces on the left
of the converted argument, but the 0 and
- flags may be used to specify padding with
zeroes on the left or with spaces on the right,
respectively. If the minimum field width is specified as
rather than a number, then the next argument
to the format command determines the minimum
field width; it must be a numeric string.
Specifies that the converted argument should be left-justified
in its field (numbers are normally right-justified with leading
spaces if needed).
Specifies that a number should always be printed with a sign,
even if positive.
Specifies that a space should be added to the beginning of the
number if the first character is not a sign.
Specifies that the number should be padded on the left with
zeroes instead of spaces.
Requests an alternate output form. For o and
O conversions it guarantees that the first digit
is always 0. For x or X
conversions, 0x or 0X (respectively)
will be added to the beginning of the result unless it is
zero. For all floating-point conversions (e,
E, f, g, and G) it
guarantees that the result always has a decimal point. For
g and G conversions it specifies that
trailing zeroes should not be removed.
The fourth portion of a conversion specifier is a
precision, which consists of a period followed by a
number. The number is used in different ways for different
conversions. For e, E, and f
conversions it specifies the number of digits to appear to
the right of the decimal point. For g and
G conversions it specifies the total number of
digits to appear, including those on both sides of the
decimal point (however, trailing zeroes after the decimal
point will still be omitted unless the # flag has
been specified). For integer conversions, it specifies a
minimum number of digits to print (leading zeroes will be
added if necessary). For s conversions it
specifies the maximum number of characters to be printed;
if the string is longer than this then the trailing
characters will be dropped. If the precision is specified
with rather than a number then the next
argument to the format command determines the
precision; it must be a numeric string.
The fourth part of a conversion specifier is a length
modifier, which must be h or l. The
h modifier specifies that the numeric value
should be truncated to a 16-bit value before converting.
This option is rarely useful. The l modifier is
The last thing in a conversion specifier is an alphabetic character
that determines what kind of conversion to perform.
The following conversion characters are currently supported:
For the numerical conversions the argument being converted must
be an integer or floating-point string; format converts the argument
to binary and then converts it back to a string according to
the conversion specifier.
No conversion: just insert %.
Convert integer to the 8-bit character it represents.
Convert integer to signed decimal string.
e or E
Convert floating-point number to scientific notation in the
form x.yyye±zz, where the number of
ys is determined
by the precision (default: 6).
If the precision is 0 then no decimal point is output.
If the E form is used then E is
printed instead of e.
Convert floating-point number to signed decimal string of
the form xx.yyy, where the number of ys is determined by
the precision (default: 6).
If the precision is 0 then no decimal point is output.
g or G
If the exponent is less than -4 or greater than or equal to the
precision, then convert floating-point number as for %e or
Otherwise convert as for %f.
Trailing zeroes and a trailing decimal point are omitted.
Convert integer to signed decimal string; the integer may either be
in decimal, in octal (with a leading 0) or in hexadecimal
(with a leading 0x).
Convert integer to unsigned octal string.
No conversion; just insert string.
Convert integer to unsigned decimal string.
x or X
Convert integer to unsigned hexadecimal string, using digits
``0123456789abcdef'' for x and ``0123456789ABCDEF'' for X).
Differences from ANSI sprintf
The behavior of the format command is the same as the
ANSI C sprintf procedure except for the following
%p and %n specifiers are not currently supported.
For %c conversions the argument must be a decimal string,
which will then be converted to the corresponding character value.
The l modifier is ignored; integer values are always converted
as if there were no modifier present and real values are always
converted as if the l modifier were present (that is, type
double is used for the internal representation).
If the h modifier is specified then integer values are truncated
to short before conversion.
02 June 2005
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 - 02 June 2005