title: return a string containing billion characters
body: <p>Hi i have a function that takes an integer number n and returns a string that contains the numbers from 1 to n separated by ','. Now this number integer n could be any number as large as 1 billion. What could be the best solution for this. And how do i manage the memory related issues like if the RAM is just 2 Gb so what would happen if i return this big string in C#. The function signature is:</p>
  
  <pre><code>string convtostr (int n)
  {}
  </code></pre>
  
  <p>so the input for e.g. could be n = 5, then output would be a string like this
      "1,2,3,4,5"</p>