Clean way to break very long line

[Eligijus]

What is the best way to break long line like this:

ui->buttonTracer2->setText(QString("x: %1 \n y: %2").arg(QString::number(static_cast<double>(convert.SamplesToRangemm(myTracer->position->key(), parse.getPulse().DS.at(0), parse.getFixed().GI))/1000000), QString::number(myTracer->position->value())));

or should i just put it in another function and assign function calls to variables?

[mrjj]

well
one way is to use variables
auto tracer_key=myTracer->position->key();
auto Pulse = parse.getPulse().DS.at(0);
auto Fixed = parse.getFixed().GI));
etc
ui->buttonTracer2->setText(QString("x: %1 \n y: %2").arg(QString::number(static_cast<double>(convert.SamplesToRangemm(tracer_key, Pulse, Fixed/1000000), QString::number(myTracer->position->value())));

that also allows for check the values before use.

update: yes. i would but in function./ use variables :)

Also just breaking it , makes it more readable. ( IMHO)

ui->buttonTracer2->setText(
    QString("x: %1 \n y: %2").arg(
    QString::number(static_cast<double>(convert.SamplesToRangemm(myTracer->position->key(), 
    parse.getPulse().DS.at(0), parse.getFixed().GI)) / 1000000), 
    QString::number(myTracer->position->value())));;

[JKSH]

@mrjj said in Clean way to break very long line:

Also just breaking it , makes it more readable. ( IMHO)

+1

You can use multiple levels of nesting to break:

ui->buttonTracer2->setText(
        QString("x: %1 \n y: %2").arg(
                QString::number(
                        static_cast<double>(
                                convert.SamplesToRangemm(
                                        myTracer->position->key(),
                                        parse.getPulse().DS.at(0),
                                        parse.getFixed().GI
                                )
                        ) / 1000000
                ),
                QString::number(myTracer->position->value())
        )
);

You can mix intermediate variables with breaks:

auto xStr = QString::number(
        static_cast<double>(
                convert.SamplesToRangemm(
                        myTracer->position->key(),
                        parse.getPulse().DS.at(0),
                        parse.getFixed().GI
                )
        ) / 1000000
);

auto yStr = QString::number(myTracer->position->value());

ui->buttonTracer2->setText(
        QString("x: %1 \n y: %2").arg(xStr, yStr)
);

Alternatively, your final line can use string concatenation instead of replacement via arg():

ui->buttonTracer2->setText("x: " + xStr + "\n y: " + yStr);

Finally, you can simplify your code. Note that:

• QString::arg() has overloads that takes int, double, etc. so you don't need to call QString::number()
• You can implicitly cast the return value of SamplestoRangemm() into a double by dividing it with a double literal, so you don't need the static_cast

auto xVal = convert.SamplesToRangemm(
        myTracer->position->key(),
        parse.getPulse().DS.at(0),
        parse.getFixed().GI
) / 1000000.0;
// The compiler treats "1000000.0" as a double, so it implicitly casts your result to a double

auto yVal = myTracer->position->value();

ui->buttonTracer2->setText(
        QString("x: %1 \n y: %2").arg(xVal).arg(yVal)
);

NOTE: What's the "best" way to indent lines, or whether an implicit cast is "better" than static_cast, are discussion topics for another day.