Remove trailing zeroes from QString Scientific notation

Isidro Perla

I have this code, the result it´s a scientific notation value, but returns a lot of traling zeroes(right zeroes)

QString cStyleResult = QString::number(valor.toDouble(), 'e');
cStyleResult.replace("e", "x10<sup>");

QRegExp reg("(e[+-])([0]+)([0-9]+)");
int pos = reg.indexIn(cStyleResult);
if(pos!=-1){
cStyleResult.replace(reg,reg.cap(1) + reg.cap(3));
}

Someone have a idea how can I erase trailing zeros in scientific notation result in QString????

KroMignon

@Isidro-Perla said in Remove trailing zeroes from QString Scientific notation:

Someone have a idea how can I erase trailing zeros in scientific notation result in QString????

Do not use QString::number(), but QString::arg()

QString cStyleResult = QString("%1").arg(valor.toDouble(), -1, 'e');

Isidro Perla

Well, I check your solution, but I still have the problem,

For example

valor = 0.48

my code print 0.4800000x10-1

I want to erase the right zeros next to .48, Some idea here??

fcarney

@Isidro-Perla

Do not use QString::number(), but QString::arg()

The link shows the answer.

        double d = 12.34;
        QString str1 = QString("delta: %1").arg(d, 0, 'e');
        QString str2 = QString("delta: %1").arg(d, 0, 'e', 3);
        qInfo() << str1;
        qInfo() << str2;

Output:

"delta: 1.234000e+01"
"delta: 1.234e+01"

Isidro Perla

Thanks it found, but I want to know
for example

double d = 128957857;
QString str2 = QString("delta: %1").arg(d, 0, 'e', 3);
qInfo() << str2;

Output:

"delta: 1,290e+08"

I want to show

"delta: 1.289579e+08;" I dont wanted to round to 3 decimals, I want to erase only right 0 from the decimal value.

JonB

@Isidro-Perla
Since I do not think there is a format which does "only remove trailing 0s", you may have to do it via QRegularExpression on the generated string.

fcarney

There is probably a cleaner way to do this:

                double d2 = 128957857;
                QString str3 = QString("%1").arg(d2, 0, 'e', 3);
                bool founde = false;
                QString str4;
                for(auto i=str3.rbegin(); i!=str3.rend(); ++i){
                    //qInfo() << *i << (*i == QChar('e'));
                    if(*i == QChar('e')){
                        founde = true;
                        str4.insert(0,*i);
                        continue;
                    }
                    if(founde){
                        if(*i != QChar('0')){
                            str4.insert(0,*i);
                            founde = false;
                        }
                    }else{
                        str4.insert(0,*i);
                    }
                }
                qInfo() << str3;
                qInfo() << str4;

output:

"1.290e+08"
"1.29e+08"

fcarney

This is cleaner:

        double d2 = 128957857;
        QString str3 = QString("%1").arg(d2, 0, 'e', 3);
        bool founde = false;
        QString str4;
        for(auto i=str3.rbegin(); i!=str3.rend(); ++i){
            if(founde){
                if(*i == QChar('0'))
                    continue;
            }else{
                if(*i == QChar('e')){
                    founde = true;
                }
            }

            str4.insert(0,*i);
        }
        qInfo() << str3;
        qInfo() << str4;

JonB

I was thinking more of (untested):

double d = 128957857;
QString str1 = QString("%1").arg(d, 0, 'e');
qInfo() << str1.replace(QRegularExpression("0+e", "e"));