title: Why would one use nested classes in C++?
body: <p>Can someone please point me towards some nice resources for understanding and using nested classes? I have some material like Programming Principles and things like this <a href="https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/com.ibm.zos.v2r1.cbclx01/cplr061.htm" rel="noreferrer"><em>IBM Knowledge Center - Nested Classes</em></a></p>
  
  <p>But I'm still having trouble understanding their purpose. Could someone please help me?</p>