read a .txt file and store it in a double array

[high_flyer]

Back in C++ I used to do:

Lets get this straight:
Qt IS C++ code!
Just like you don't differentiate between STL or boost and c++, so you don't with Qt.
Do you understand the concept of a library?

Should i do read it line by line or store it directly to variable.

Reading line by line is still just reading.
Storing in something else - they are not exclusive.

suppose in Qt there are lots of overloaded functions and classes that let you do this

What is 'this'?
Reading from a file?
Storing your data in an array?
All of the above?

And you are right - there are a lot of Classes in Qt.

but I haven't found them yet

Here is the full list:
http://doc.trolltech.com/4.7/classes.html

It seems you are aware of streams, as you have posted in your code.
So why not start for example by searching for streams in the Qt documentation?
If you are aware of streams, you probably are also aware of vectors, which you could also look in the Qt docs.
Usually the Qt classes have very sensible name, so searching for "file" in the class list will give you some good hits to what you might be looking for, if for example you need some file handling classes.
Qt has many STL classes reimplemented, take the time to read the documentation.

[fatecasino]

What is 'this'?
Reading from a file?
Storing your data in an array?
All of the above?

reading the file->taking the actual data that you need->passing the data to a vector/array


The Documentation is fantastic, but there are tens of classes and functions related to "file". There is no reason to start checking each one of them.Knowledge is not built in this way.
I started this thread expecting something like:

for reading a file, try using Qxxxxx
for obtaining the actual data that you need from the file, try using Qzzzzz
for passing this data to a vector/array, try using Qrrrrrrr

Then I would go directly to The Documentation to learn how to use Qxxxxx,Qzzzzz,Qrrrrrrr

[marcvanriet]

Hi,

In addition to using the 'old' C++ streams, you have the option to use QFile and QTextStream. Directly from the Qt documentation :

QFile file("in.txt");
     QTextStream in(&file);
     while (!in.atEnd()) {
         QString line = in.readLine();
         // process your line here
     }

QFile file("in.txt");
     QTextStream in(&file);
     while (!in.atEnd()) {
         QString line = in.readLine();
         // process your line here
     }

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Then, you can use QString::Split to split your line with two numbers into 2 strings, and QString::toDouble() to convert it to a double. The previously mentioned vector and list classes can be used to store the points.

Best regards,
Marc