How to get rid of scientific notation while converting from QString to float

[Swati777999]

Here's my code

    QString myStr ="03145678";
    qDebug() <<"String input ="<<myStr;   // String input = "03145678"
    float myFloat = myStr.toFloat();
    qDebug()<< "String to float conversion = " << myFloat;   //= 3.14568e+06

I don't want the result as 3.14568e+06 , I want to display it as 03145678 without losing any digit.

When I tried it with .toInt() , I got the result as 3145678 by losing the leading zero.

How can I retain all the digits of the String while converting it to other data types like float,double or int ?

[Pl45m4]

@Swati777999

Same answer as here: Change the qDebug notation.
Haven't tried but there's something like Qt::fixed and Qt::scientific which you can use in your print command.

• https://doc.qt.io/qt-5/qtextstream.html#RealNumberNotation-enum

Edit:

Similar topic here:

• https://forum.qt.io/topic/75586/showing-numbers-in-decimal-not-scientific-notation

[JKSH]

qDebug() is for quickly checking your data.

If you want to format and display your data, convert it to a QString with the exact formatting that you want. Then, display it in a QLabel or another display widget.

[Swati777999]

@JKSH said in How to get rid of scientific notation while converting from QString to float:

qDebug() is for quickly checking your data.

If you want to format and display your data, convert it to a QString with the exact formatting that you want. Then, display it in a QLabel or another display widget.

I'm running this code in Qt console.

[JKSH]

@Swati777999 said in How to get rid of scientific notation while converting from QString to float:

I'm running this code in Qt console.

OK, then use QTextStream to print to stdout.

You cal call the following functions to format your numbers:

• QTextStream::setNumberFlags()
• QTextStream::setRealNumberNotation()
• QTextStream::setFieldWidth()
• QTextStream::setPadChar()

[Swati777999]

@JKSH said in How to get rid of scientific notation while converting from QString to float:

@Swati777999 said in How to get rid of scientific notation while converting from QString to float:

I'm running this code in Qt console.

OK, then use QTextStream to print to stdout.

You cal call the following functions to format your numbers:

• QTextStream::setNumberFlags()
• QTextStream::setRealNumberNotation()
• QTextStream::setFieldWidth()
• QTextStream::setPadChar()

It's so frustrating not to see the code working correctly when you follow Qt Docs.

    QString myStr ="03145678";
    qDebug() <<"String input ="<<myStr;
    qDebug()<<"After applying QTextStream = <<" << QTextStream::setRealNumberNotation(myStr::2); //Syntax Error

I am unable to understand the synatx from the Qt Doc. :( and it's so frustrating for me!

[jsulm]

@Swati777999 said in How to get rid of scientific notation while converting from QString to float:

setRealNumberNotation

You know that this is NOT a static method?
Also, why do you mix qDebug and QTextStream? This is NOT what @JKSH suggested.

QTextStream out(stdout);
out.setRealNumberNotation...
out << ...

[KroMignon]

@Swati777999 said in How to get rid of scientific notation while converting from QString to float:

It's so frustrating not to see the code working correctly when you follow Qt Docs.

QString myStr ="03145678";
qDebug() <<"String input ="<<myStr;
qDebug()<<"After applying QTextStream = <<" << QTextStream::setRealNumberNotation(myStr::2); //Syntax Error

I am unable to understand the synatx from the Qt Doc. :( and it's so frustrating for me!

I don't want to hurt you, but this is standard C++ syntax. As I already told you C++ and Python are 2 different languages in almost all aspects.
So if you want to develop in C++ you have to learn C++ basics, as you have done for python.

C++ is not better or worst than python, it is just completely different.

The C++ code you have written don't make sense, so it cannot work:

• myStr::2 is non sense, this would mean you want to get a static member called 2 (which is not allowed a member name!) from class used by myStr, which is QString
• QTextStream::setRealNumberNotation() means in C++ that you want to call static method setRealNumberNotation of calss QTextStream which do not exists!

So please, take time to learn C++ if you want to program in C++.

[SimonSchroeder]

@Swati777999 said in How to get rid of scientific notation while converting from QString to float:

When I tried it with .toInt() , I got the result as 3145678 by losing the leading zero.

There is no built-in number type that would store leading zeros. If this is what you want you need to look for another solution. You can specify the width of the output with a padding of '0's to the left. What kind of numbers do you want to handle? What do they represent? Why should they have a leading zero?