What does |= signify in C++? : <p>I was going through the source code of Intel's deep learning framework Caffe, when I came across <code>|=</code>. I've never seen that before in any code. In fact, I found it twice in the code. <a href="https://github.com/intel/caffe/blob/master/src/caffe/net.cpp#L188" rel="nofollow noreferrer">Line 188</a>:</p>

<pre><code>need_backward |= blob_need_backward_[blob_id];
</code></pre>

<p>and <a href="https://github.com/intel/caffe/blob/master/src/caffe/net.cpp#L254" rel="nofollow noreferrer">line 254</a>:</p>

<pre><code>need_backward |= param_need_backward;
</code></pre>

<p>I realize that they both are housed in a for loop which might signify some kind of relation. I'm just assuming. </p>
