Libc-391.tar.gz

[apple/libc.git] / stdio / FreeBSD / printf.3

diff --git a/stdio/FreeBSD/printf.3 b/stdio/FreeBSD/printf.3
index e10be251546d8e2068d185e06baf30b5b34223e2..a14c8feff0f58c2023fa44aa9dbcadecc822c584 100644 (file)
--- a/stdio/FreeBSD/printf.3
+++ b/stdio/FreeBSD/printf.3
@@ -34,9 +34,9 @@
 .\" SUCH DAMAGE.
 .\"
 .\"     @(#)printf.3   8.1 (Berkeley) 6/4/93
-.\" $FreeBSD: src/lib/libc/stdio/printf.3,v 1.55 2003/01/06 06:19:19 tjr Exp $
+.\" $FreeBSD: src/lib/libc/stdio/printf.3,v 1.58 2004/10/16 16:00:01 stefanf Exp $
 .\"
-.Dd January 4, 2003
+.Dd October 16, 2004
 .Dt PRINTF 3
 .Os
 .Sh NAME
@@ -365,6 +365,8 @@ or
 conversion:
 .Bl -column ".Sy Modifier" ".Cm a , A , e , E , f , F , g , G"
 .It Sy Modifier Ta Cm a , A , e , E , f , F , g , G
+.It Cm l No (ell) Ta Vt double
+(ignored, same behavior as without it)
 .It Cm L Ta Vt "long double"
 .El
 .Pp
@@ -517,30 +519,21 @@ decimal point appears only if it is followed by at least one digit.
 .It Cm aA
 The
 .Vt double
-argument is converted to hexadecimal notation in the style
+argument is rounded and converted to hexadecimal notation in the style
 .Sm off
 .Oo \- Oc Li 0x Ar h Li \&. Ar hhhp Oo \\*[Pm] Oc Ar d ,
 .Sm on
 where the number of digits after the hexadecimal-point character
 is equal to the precision specification.
-If the precision is missing, it is taken as enough to exactly
-represent the floating-point number; if the precision is
-explicitly zero, no hexadecimal-point character appears.
-This is an exact conversion of the mantissa+exponent internal
-floating point representation; the
-.Sm off
-.Oo \- Oc Li 0x Ar h Li \&. Ar hhh
-.Sm on
-portion represents exactly the mantissa; only denormalized
-mantissas have a zero value to the left of the hexadecimal
-point.
+If the precision is missing, it is taken as enough to represent
+the floating-point number exactly, and no rounding occurs.
+If the precision is zero, no hexadecimal-point character appears.
 The
 .Cm p
 is a literal character
-.Ql p ;
-the exponent is preceded by a positive or negative sign
-and is represented in decimal, using only enough characters
-to represent the exponent.
+.Ql p ,
+and the exponent consists of a positive or negative sign
+followed by a decimal number representing an exponent of 2.
 The
 .Cm A
 conversion uses the prefix
@@ -556,6 +549,21 @@ to represent the hex digits, and the letter
 (rather than
 .Ql p )
 to separate the mantissa and exponent.
+.Pp
+Note that there may be multiple valid ways to represent floating-point
+numbers in this hexadecimal format.
+For example,
+.Li 0x3.24p+0 , 0x6.48p-1
+and
+.Li 0xc.9p-2
+are all equivalent.
+The format chosen depends on the internal representation of the
+number, but the implementation guarantees that the length of the
+mantissa will be minimized.
+Zeroes are always represented with a mantissa of 0 (preceded by a
+.Ql -
+if appropriate) and an exponent of
+.Li +0 .
 .It Cm C
 Treated as
 .Cm c
@@ -855,26 +863,6 @@ should be avoided.
 .Pp
 The
 .Nm
-family of functions currently lack the ability to use the
-.Cm '
-flag in conjunction with the
-.Cm f
-conversion specifier.
-The
-.Cm a
-and
-.Cm A
-conversion specifiers have not yet been implemented.
-The
-.Cm L
-modifier for floating point formats simply round the
-.Vt "long double"
-argument to
-.Vt double ,
-providing no additional precision.
-.Pp
-The
-.Nm
 family of functions do not correctly handle multibyte characters in the
 .Fa format
 argument.