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