How can I add a dropdown menu icon
I have this code
<div class="btn-group" dropdown> <button type="button" class="btn btn-danger">Action</button> <button type="button" class="btn btn-danger dropdown-toggle" dropdown-toggle> <span class="caret"></span> <span class="sr-only">Split button!</span> </button> <ul class="dropdown-menu" role="menu"> <li><a href="#">Action</a></li> <li><a href="#">Another action</a></li> <li><a href="#">Something else here</a></li> <li class="divider"></li> <li><a href="#">Separated link</a></li> </ul> </div> which looks like

I want to add an icon like cog insteaqd from text like this

I tried this
<button type="button" class="glyphicon glyphicon-cog"></button>
but does not work
For a button, the icon should be inside the button as the contents of the button, so instead of <button type="button" class="glyphicon glyphicon-cog"></button> it should be
<button type="button" class="btn"> <span class="glyphicon glyphicon-cog"></span> </button> Edit: to add a <span class="caret"></span> to Bootstrap, you use <span class="caret"></span>
Thus, the final result, to get a button with a hexadecimal and drop-down menu, looks like this:
<button type="button" class="btn"> <span class="glyphicon glyphicon-cog"></span><span class="caret"></span> </button> When I paste this code into the Bootstrap homepage, I get the following: 
<div class="btn-group" dropdown> <button type="button" class="btn btn-danger"><span class="glyphicon glyphicon-cog"></span></button> <button type="button" class="btn btn-danger dropdown-toggle" dropdown-toggle> <span class="caret"></span> <span class="sr-only">Split button!</span> </button> <ul class="dropdown-menu" role="menu"> <li><a href="#">Action</a></li> <li><a href="#">Another action</a></li> <li><a href="#">Something else here</a></li> <li class="divider"></li> <li><a href="#">Separated link</a></li> </ul> </div> You can use this code