Output long double to console

Question

I tried to output a long double to the console directly using qDebug() and indirectly via QString::number() but both do not accept long double.

Is it true that there is no easy way of printing a long double floating point number to the console using Qt? Why?!

Since a `long double` does not need to take any more space then a `double` they may have felt it was pointless. — NathanOliver, Jul 11 '16 at 20:09
@NathanOliver: That depends on your platform. 16-bit Windows uses 80 bits for `long double` and 64 bits for `double`. I wouldn't be surprised if there are other examples. — Adrian McCarthy, Jul 11 '16 at 21:22
You can use this http://stackoverflow.com/questions/2326850/long-double-to-string — demonplus, Jul 12 '16 at 05:34

Toby Speight · Answer 1 · 2016-07-12T22:40:47.583

You can provide your own overload of operator<<():

QDebug& operator<<(QDebug& d, long double f)
{
    return d << static_cast<double>(f);
}

This won't show you any extra precision, of course, but may be what you need.

Be aware, however, that a future version of Qt might implement such a function, putting you in violation of the One-Definition Rule. To avoid this, you should guard it with an appropriate #if test for the exact Qt version (or range of versions) that you have verified do not provide a conflicting definition. Also, please consider contributing your implementation to Qt.

score 0 · Accepted Answer · answered Jul 12 '16 at 22:00

0

There's no overarching reason. At least as of Qt 5.6, nobody bothered to implement it. That's all.

answered Jul 12 '16 at 22:00

Kuba hasn't forgotten Monica

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Output long double to console

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