title: Invalid types float[int] for array subscript
body: <p>I had been doing a question. I have not written the function code here because  I am getting an error:</p>
  
  <blockquote>
    <p>invalid types float[int] for array subscript in the following code snippet. </p>
  </blockquote>
  
  <p>Please tell me why is this <code>error</code> coming?</p>
  
  <pre><code>#include&lt;iostream&gt;
  using namespace std;
  main()
  {
      float a,b,p,q,r,s,arr[1000];
      int n=1000, minOp;
  
    cin&gt;&gt;a;
    cin&gt;&gt;b;
    cin&gt;&gt;p&gt;&gt;q&gt;&gt;r&gt;&gt;s;
    arr[0]=src;
    for(int i=1; i&lt;n; i++)
    {
        if( i%4==1)
        {
            a[i]=a[i/4] + p;
        }
        else if( i%4==2)
        {
            a[i]=a[i/4] - q;
        }
        else
        if( i%4==3)
        {
            a[i]=a[i/4] * r;
        }
        else if( i%4==0)
        {
  
            a[i]= a[ (i/4)-1] / s;
        }
      }
  
   root = buildTree( arr, n);
   minOp = bfs(root,b);
  cout&lt;&lt;minOp;
  }
  </code></pre>
  
  <p>Any help would be appreciated.</p>