April 06, 2013 [Issue 9889] New: Incorrect rounding on floating value formatting | ||||
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http://d.puremagic.com/issues/show_bug.cgi?id=9889 Summary: Incorrect rounding on floating value formatting Product: D Version: D2 Platform: All OS/Version: Windows Status: NEW Keywords: wrong-code Severity: normal Priority: P2 Component: Phobos AssignedTo: nobody@puremagic.com ReportedBy: verylonglogin.reg@gmail.com --- Comment #0 from Denis Shelomovskij <verylonglogin.reg@gmail.com> 2013-04-06 13:51:19 MSD --- `std.format.formatValue` uses C's `snprintf` which works this way in `snn.lib`: --- import std.string; void main() { assert(format("%.1f", 0.09) == "0.1"); // Failed, formatted as "0.0" assert(format("%.1f", -0.09) == "-0.1"); // Failed, formatted as "-0.0" assert(format("%.1f", 0.095) == "0.1"); // OK assert(format("%.1f", -0.095) == "-0.1"); // OK assert(format("%.1f", 0.094) == "0.1"); // Failed, formatted as "0.0" assert(format("%.1f", -0.094) == "-0.1"); // Failed, formatted as "-0.0" } --- Workaround: --- real preformatFloating(real n, ubyte digits) { immutable k = 10.0L ^^ digits; return round(n * k) / k; } void main() { assert(format("%.1f", preformatFloating(0.09, 1)) == "0.1"); } --- -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
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