How to make a lineEdit show decimal numbers instead of scientific

[franky]

Hi all,

This is a section of my app which is a calculator in Qt:

QString ss;
 QTextStream (&ss) << expression();  // expression() return a double value
 result_box -> setText(ss); // result_box is a lineEdit

QString ss;
 QTextStream (&ss) << expression();  // expression() return a double value
 result_box -> setText(ss); // result_box is a lineEdit

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When I type 10^6 and the function expression() returns that value, in result_box the scientific notation of it will be shown, 1e+06!

How to do to make the app show the result in decimal, 1000000 rather than that scientific notation please?

[ChrisW67]

result_box->setText( QString::number(expression(), 'f', 0) );

result_box->setText( QString::number(expression(), 'f', 0) );

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[Gokulnathvc]

You can use like the following::

result_box->setText( QString::number(expression(), 'd', 0) );

[Ginsengelf]

Using 'd' is not explicitely defined. It works only because QString::number() defaults to 'f' if any undefined character is used.
As you can see from this small example, 'd', 'q', 'a', '#' all produce the same output.

#include <QtCore/QCoreApplication>
 
#include <QDebug>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    double dValue = 123e15;
 
    qDebug () << 'g' << QString::number (dValue, 'g', 0);
    qDebug () << 'f' << QString::number (dValue, 'f', 0);
 
    qDebug () << 'd' << QString::number (dValue, 'd', 0);
    qDebug () << 'a' << QString::number (dValue, 'a', 0);
    qDebug () << 'q' << QString::number (dValue, 'q', 0);
    qDebug () << '#' << QString::number (dValue, '#', 0);
 
    return a.exec();
}

#include <QtCore/QCoreApplication>

#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    double dValue = 123e15;

    qDebug () << 'g' << QString::number (dValue, 'g', 0);
    qDebug () << 'f' << QString::number (dValue, 'f', 0);
    
    qDebug () << 'd' << QString::number (dValue, 'd', 0);
    qDebug () << 'a' << QString::number (dValue, 'a', 0);
    qDebug () << 'q' << QString::number (dValue, 'q', 0);
    qDebug () << '#' << QString::number (dValue, '#', 0);

    return a.exec();
}

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Output:
g "1e+17"
f "123000000000000000"
d "123000000000000000"
a "123000000000000000"
q "123000000000000000"
# "123000000000000000"

But please do not use undefined values. They might get meaningful in the future, and you would get unexpected results. As ChrisW67 already wrote using 'f' is the way to go.

Ginsengelf