Writing to a CSV file type

Steven_DAntonio

HI,

I'm trying to write a set of data to a CSV file in Qt 5.6 on a windows machine.

So far I have

// Save as a CSV file

QString species;

species = ui->tBSpecies->text();

QFile file("./file.csv");
if (file.open(QFile::WriteOnly|QFile::Truncate))
{
QTextStream stream(&file);
stream << species << "\t" << gType << "\t" << species << "\t" << tSLen << "\t" << tSWidth << "\t" << tSThick << "\t"
<< tSMass << "\t" << den << "\t" << fLong << "\t" << fCross << "\t" << fDiag << "\t"
<< eLong << "\t" << eCross << "\t" << eDiag << "\t" << eG << "\t" << targetThick << "\n"; // this writes first line with two columns

file.close();

Most of the variables are doubles and come in from another function (species and gType are the only strings).

The part I am having trouble with is looking at the CSV file to see if it already contains data and placing the new data in the first open row so that i do not overwrite existing data.

Anything that points me in the right direction would be great.

Thank you
Steven

? Offline

@Steven_DAntonio Hi!

if it already contains data and placing the new data in the first open row

Then why do you use QIODevice::Truncate? I think QIODevice::Append would be the right choice in this case.

kshegunov

@Steven_DAntonio said:

The part I am having trouble with is looking at the CSV file to see if it already contains data and placing the new data in the first open row so that i do not overwrite existing data.

Are you trying to update rows that are already written? If so, you can't. CSV is a text file, so this won't work. If you only want to append, see @Wieland's suggestion.

Steven_DAntonio

HI,

Thank you for the replies, it looks like the append function is just what I may be looking for. I'm not trying to change any values, in fact changing anything that is written previously is just what I want to avoid. What I'm looking to do is to keep the order (species (the first variable) is always saved to column 1 of the first available empty row, gType to the second etc.