title: Using key value in C++
body: <p>I'm new to C++, previous experience with java. How can I implement a key - value structure like in a java hashmap.</p>
  
  <p>I want the structure to map <code>float</code> to my defined class <code>matrix</code>.</p>
  
  <p>How can I declare the structure, add to it, get from it.</p>
  
  <p>Any help is appreciated.</p>