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  1. Qt
  2. QTBUG-88371

QString::toFloat() fails on specific input

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P3: Somewhat important
    • Resolution: Unresolved
    • Affects Version/s: 5.15.1
    • Fix Version/s: None
    • Labels:
      None
    • Platform/s:
      Windows

      Description

      Dear all,

      I am reading strings representing floats and converting them to float using QString()::toFloat().

      I noticed that on some inputs, this conversion fails (but toDouble() succeeds).

      Example:

      String: "-3.4028235e+038" (equivalent to 0xFFFF7FFF as LE-4byte float)

      Reading this with toFloat(&ok) fails (ok = false), using toDouble(&ok) works as expected.

       

      Interestingly, Qt can not parse its own output when using this float, converting it to QString using QString::number(f, 'g', 8) and trying to parse this QString again with toFloat().

       

      You can find a minimal example attached. Cases A and B show the conversion using toFloat() failing, cases C and D show the conversion of the same numbers succeed with toDouble().

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            Assignee:
            thiago Thiago Macieira
            Reporter:
            phiber Philipp Berger
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              Dates

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              Updated:

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