Here we will use the {\tt it\_\-file} class to store some data. The program {\tt write\_\-it\_\-file.cpp} looks as follows:



\begin{DocInclude}\begin{verbatim}#include <itpp/itcomm.h>

using namespace itpp;

int main()
{
  // Declare the it_file class
  it_file ff;

  // Open a file with the name "it_file_test.it"
  ff.open("it_file_test.it");

  // Create some data to put into the file
  vec a = linspace(1, 20, 20);

  // Put the variable a into the file. The Name("a") tells the file class
  // that the next variable shall be named "a".
  ff << Name("a") << a;

  // Force the file to be written to disc. This is useful when performing
  // iterations and ensures that the information is not stored in any cache
  // memory. In this simple example it is not necessary to flush the file.
  ff.flush();

  // Close the file
  ff.close();

  // Exit program
  return 0;
}
\end{verbatim}
\end{DocInclude}


When you run this program you will obtain a file called {\tt it\_\-file\_\-test.it} in your current directory. You can read the file into Matlab/Octave to view the data by using the following commands:



\begin{Code}\begin{verbatim}itload('it_file_test.it')
figure(1); clf;
plot(a)
\end{verbatim}
\end{Code}



Note: Make sure that {\tt \$PREFIX/share/itpp} is in your Matlab/Octave path and that you run the code above from the directory where {\tt it\_\-file\_\-test.it} is located ({\tt \$PREFIX} is the IT++ installation prefix; {\tt /usr/local} by default).

The IT++ program {\tt read\_\-it\_\-file.cpp} that reads the file and prints its content can look like this:



\begin{DocInclude}\begin{verbatim}\end{verbatim}
\end{DocInclude}


Here is the output of the program:



\footnotesize\begin{verbatim}
a = [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20]
\end{verbatim}
\normalsize