archie/tcl7.6/doc/PrintDbl.3

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'\" SCCS: @(#) PrintDbl.3 1.6 96/03/25 20:05:45
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.so man.macros
.TH Tcl_PrintDouble 3 7.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_PrintDouble \- Convert floating value to string
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_PrintDouble\fR(\fIinterp, value, dst\fR)
.SH ARGUMENTS
.AS Tcl_Interp *interp
.AP Tcl_Interp *interp in
Interpreter that controls the conversion.
.AP double value in
Floating-point value to be converted.
.AP char *dst out
Where to store string representing \fIvalue\fR.  Must have at
least TCL_DOUBLE_SPACE characters of storage.
.BE

.SH DESCRIPTION
.PP
\fBTcl_PrintDouble\fR generates a string that represents the value
of \fIvalue\fR and stores it in memory at the location given by
\fIdst\fR.  It uses %g format to generate the string, with two
special twists.  First, the string is guaranteed to contain either
a ``.'' or an ``e'' so that it doesn't look like an integer (where
%g would generate an integer with no decimal point, \fBTcl_PrintDouble\fR
adds ``.0'').  Second, the number of significant digits printed at
\fIdst\fR is controlled by the \fBtcl_precision\fR variable in
\fIinterp\fR;  if \fBtcl_precision\fR is undefined then 6 significant
digits are printed.

.SH KEYWORDS
conversion, double-precision, floating-point, string