title: Largest floating point variable
body: <p>The program takes for parameter one double and its doing computation with long float point values. eg <code>double myvar= n*0.000005478554 /298477</code>.
  The problem is that im not sure that the real computational value is inserted to myvar.
  because whenvever i change n it produce the same thing <code>cout&lt;&lt;"myvar ="&lt;&lt;myvar;</code>
  What is the biggest type in c++ that can be used for maximum accuracy? Does a buffer overflow caused by this code because double variable cant hold too much info ? If yes what can happen and how can i detect it for later use?</p>