tcldoc Tcl/Tk 9.0.4
/

Home › Tcl Library Procedures Tcl

Tcl_PrintDouble C API

Convert floating value to string

literal type exactly as shown argument replace with your value ?optional? may be omitted

Synopsis#

#include <tcl.h>

Tcl_PrintDouble(interp, value, dst)#

Arguments#

Tcl_Interp *interp (in)

This argument is ignored.

double value (in)

Floating-point value to be converted.

char *dst (out)

Where to store the string representing value. Must have at least TCL_DOUBLE_SPACE characters of storage.

Description#

Tcl_PrintDouble generates a string that represents the value of value and stores it in memory at the location given by dst. It uses %g format to generate the string, with one special twist: the string is guaranteed to contain either a “.” or an “e” so that it does not look like an integer. Where %g would generate an integer with no decimal point, Tcl_PrintDouble adds “.0”.

The result will have the fewest digits needed to represent the number in such a way that Tcl_NewDoubleObj will generate the same number when presented with the given string. IEEE semantics of rounding to even apply to the conversion.

Keywords#

conversion · double-precision · floating-point · string

Copyright#