title: free a double pointer
body: <p>I created a 2-D matrix using double pointer like that:</p>
  
  <pre><code>int** pt; pt = (int*) malloc(sizeof(int)*10);
  </code></pre>
  
  <p>I know that a pointer is freed like that</p>
  
  <pre><code>free(ptr);
  </code></pre>
  
  <p>How can we free the double pointer?</p>
  
  <p>What if we print something and later freed that memory and exit the program? Does the final memory consist of that which we used or it will be same as initial?</p>