52 lines
1.9 KiB
Groff
52 lines
1.9 KiB
Groff
'\"
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'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tcl_PrintDouble 3 8.0 Tcl "Tcl Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tcl_PrintDouble \- Convert floating value to string
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.SH SYNOPSIS
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.nf
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\fB#include <tcl.h>\fR
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.sp
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\fBTcl_PrintDouble\fR(\fIinterp, value, dst\fR)
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.SH ARGUMENTS
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.AS Tcl_Interp *interp out
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.AP Tcl_Interp *interp in
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Before Tcl 8.0, the \fBtcl_precision\fR variable in this interpreter
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controlled the conversion. As of Tcl 8.0, this argument is ignored and
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the conversion is controlled by the \fBtcl_precision\fR variable
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that is now shared by all interpreters.
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.AP double value in
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Floating-point value to be converted.
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.AP char *dst out
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Where to store the string representing \fIvalue\fR. Must have at
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least \fBTCL_DOUBLE_SPACE\fR characters of storage.
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.BE
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.SH DESCRIPTION
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.PP
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\fBTcl_PrintDouble\fR generates a string that represents the value
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of \fIvalue\fR and stores it in memory at the location given by
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\fIdst\fR. It uses \fB%g\fR format to generate the string, with one
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special twist: the string is guaranteed to contain either a
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.QW .
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or an
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.QW e
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so that it does not look like an integer. Where \fB%g\fR would
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generate an integer with no decimal point, \fBTcl_PrintDouble\fR adds
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.QW .0 .
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.PP
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If the \fBtcl_precision\fR value is non-zero, the result will have
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precisely that many digits of significance. If the value is zero
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(the default), the result will have the fewest digits needed to
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represent the number in such a way that \fBTcl_NewDoubleObj\fR
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will generate the same number when presented with the given string.
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IEEE semantics of rounding to even apply to the conversion.
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.SH KEYWORDS
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conversion, double-precision, floating-point, string
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