1Tcl_PrintDouble(3) Tcl Library Procedures Tcl_PrintDouble(3)
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8 Tcl_PrintDouble - Convert floating value to string
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11 #include <tcl.h>
12 Tcl_PrintDouble(interp, value, dst)
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16 Tcl_Interp *interp (in) Before Tcl 8.0, the tcl_precision
17 variable in this interpreter con‐
18 trolled the conversion. As of Tcl
19 8.0, this argument is ignored and the
20 conversion is controlled by the
21 tcl_precision variable that is now
22 shared by all interpreters.
23 double value (in) Floating-point value to be converted.
25 char *dst (out) Where to store the string representing
27 value. Must have at least TCL_DOU‐
28 BLE_SPACE characters of storage.
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32 Tcl_PrintDouble generates a string that represents the value of value
33 and stores it in memory at the location given by dst. It uses %g for‐
34 mat to generate the string, with one special twist: the string is guar‐
35 anteed to contain either a “.” or an “e” so that it does not look like
36 an integer. Where %g would generate an integer with no decimal point,
37 Tcl_PrintDouble adds “.0”.
38 If the tcl_precision value is non-zero, the result will have precisely
40 that many digits of significance. If the value is zero (the default),
41 the result will have the fewest digits needed to represent the number
42 in such a way that Tcl_NewDoubleObj will generate the same number when
43 presented with the given string. IEEE semantics of rounding to even
44 apply to the conversion.
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47 conversion, double-precision, floating-point, string
48Tcl 8.0 Tcl_PrintDouble(3)