C++ append to existing file : <p>I'm trying to take data from multiple files and append them into one file using fstream, however whenever I try to output to an existing file using</p>

<pre><code> std::ofstream Out("mushroom.csv", std::ofstream::app);
</code></pre>

<p>it outputs to the end of the file, I want it to append to the same line, for example if this is the previous file:</p>

<pre><code> 1,2,3,4,5,6,7
 8,9,10,11,12,13
</code></pre>

<p>I want it to become:</p>

<pre><code> 1,2,3,4,5,6,7,a,b,c
 8,9,10,11,12,13,c,d,e
</code></pre>
