Qt - Add two numbers

Question

I can't get this to work. Anyone knows how to make it work?

void MainWindow::on_pushButton_clicked()
{

    int sum1 = ui->lineEdit->text().toInt();
    int sum2 = ui->lineEdit_2->text().toInt();

    ui->label_4->setText(sum1 + sum2);
}

Error:

C:\Qt\Tools\QtCreator\bin\Mellemrubrik\mainwindow.cpp:26: error: C2664: 'QLabel::setText' : cannot convert parameter 1 from 'int' to 'const QString &' Reason: cannot convert from 'int' to 'const QString' No constructor could take the source type, or constructor overload resolution was ambiguous

Please tell us what problems you are experiencing. It is not easy for us to help when the problem description is "Doesn't work" :) — Magnus Hoff, Nov 14 '13 at 17:35
Not enough jquery. =) If you can write this post, why you can't understand the compiler message? "cannot convert parameter 1 from 'int' to 'const QString &'" - so compiler can't convert your integer to Qt QString. You need to convert from int to QString explicitly. — JustAnotherCurious, Nov 26 '13 at 04:36
As it is written in the error message, it cannot convert from int to string, you need to cast the (sum1 + sum2) to a string like the solutions mentioned below, using QString::number — Majid khalili, Jan 01 '20 at 11:41

score 3 · Answer 1 · answered Nov 14 '13 at 17:45

3

In general, you can convert multiple numeric types to QStrings like so:

int val1, val2;
QString result = QString("val1=%1 val2=%2 sum=%3").arg(val1).arg(val2).arg(val1+val2);

But for numbers, this is also possible:

int val1, val2;
QString result = QString::number(val1+val2);

You can see Qt's documentation for more info!

answered Nov 14 '13 at 17:45

Alex Reinking

16,724
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What are the generic "quantities" not being numbers here? QString::number() is basically equivalent in functionality, and more concise (and more performant probably, too). So I'd always use the second variant. – Frank Osterfeld Nov 14 '13 at 17:47
The advantage to .arg() in some cases is your ability to chain them. I just updated my example to reflect this. – Alex Reinking Nov 14 '13 at 17:49

score 0 · Answer 2 · edited Jan 01 '20 at 13:06

0

You can try this

int v1,v2;
v1=ui->lineEdit->text().toInt():
v2=ui->lineEdit_2->text().toInt()
QString result = QString::number(v1+v2);
ui->label->setText(result);

edited Jan 01 '20 at 13:06

L_J

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answered Jan 01 '20 at 11:33

Shaiju K R

1

you should try and add a brief textual description to your code block. Perhaps taking "You can try this" out of the code block, and expanding slightly on the sentence. – bad_coder Jan 01 '20 at 11:56

score 0 · Answer 3 · answered Sep 05 '20 at 18:18

0

Would setNum as shown below do?

int v1,v2;
v1=ui->lineEdit->text().toInt():
v2=ui->lineEdit_2->text().toInt()
ui->label->setNum(v1+v2);

answered Sep 05 '20 at 18:18

Habibie

1

Qt - Add two numbers

3 Answers3