| 1 | '\" |
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| 2 | '\" Copyright (c) 1989-1993 The Regents of the University of California. |
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| 3 | '\" Copyright (c) 1994-1997 Sun Microsystems, Inc. |
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| 4 | '\" |
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| 5 | '\" See the file "license.terms" for information on usage and redistribution |
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| 6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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| 7 | '\" |
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| 8 | '\" RCS: @(#) $Id: PrintDbl.3,v 1.11 2007/12/13 15:22:31 dgp Exp $ |
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| 9 | '\" |
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| 10 | .so man.macros |
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| 11 | .TH Tcl_PrintDouble 3 8.0 Tcl "Tcl Library Procedures" |
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| 12 | .BS |
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| 13 | .SH NAME |
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| 14 | Tcl_PrintDouble \- Convert floating value to string |
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| 15 | .SH SYNOPSIS |
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| 16 | .nf |
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| 17 | \fB#include <tcl.h>\fR |
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| 18 | .sp |
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| 19 | \fBTcl_PrintDouble\fR(\fIinterp, value, dst\fR) |
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| 20 | .SH ARGUMENTS |
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| 21 | .AS Tcl_Interp *interp out |
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| 22 | .AP Tcl_Interp *interp in |
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| 23 | Before Tcl 8.0, the \fBtcl_precision\fR variable in this interpreter |
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| 24 | controlled the conversion. As of Tcl 8.0, this argument is ignored and |
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| 25 | the conversion is controlled by the \fBtcl_precision\fR variable |
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| 26 | that is now shared by all interpreters. |
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| 27 | .AP double value in |
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| 28 | Floating-point value to be converted. |
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| 29 | .AP char *dst out |
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| 30 | Where to store the string representing \fIvalue\fR. Must have at |
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| 31 | least \fBTCL_DOUBLE_SPACE\fR characters of storage. |
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| 32 | .BE |
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| 33 | |
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| 34 | .SH DESCRIPTION |
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| 35 | .PP |
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| 36 | \fBTcl_PrintDouble\fR generates a string that represents the value |
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| 37 | of \fIvalue\fR and stores it in memory at the location given by |
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| 38 | \fIdst\fR. It uses \fB%g\fR format to generate the string, with one |
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| 39 | special twist: the string is guaranteed to contain either a |
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| 40 | .QW . |
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| 41 | or an |
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| 42 | .QW e |
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| 43 | so that it does not look like an integer. Where \fB%g\fR would |
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| 44 | generate an integer with no decimal point, \fBTcl_PrintDouble\fR adds |
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| 45 | .QW .0 . |
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| 46 | .VS 8.5 |
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| 47 | .PP |
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| 48 | If the \fBtcl_precision\fR value is non-zero, the result will have |
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| 49 | precisely that many digits of significance. If the value is zero |
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| 50 | (the default), the result will have the fewest digits needed to |
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| 51 | represent the number in such a way that \fBTcl_NewDoubleObj\fR |
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| 52 | will generate the same number when presented with the given string. |
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| 53 | IEEE semantics of rounding to even apply to the conversion. |
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| 54 | .VE |
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| 55 | |
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| 56 | .SH KEYWORDS |
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| 57 | conversion, double-precision, floating-point, string |
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