Text reading and string inputting program
I wonder if you even have tested this program:

This:


  while (!info.EndOfStream)
  {
    String tempstring = String.Empty;
    tempstring = reader.ReadLine();

    while (!reader.EndOfStream)
    {



will run forever because info is never read from and will never reach EOS.



In the context this:


   while (!info.EndOfStream)    {
     String tempstring = String.Empty;
     tempstring = reader.ReadLine();



is not understandable. Do you have the tempstring that is going to be written instead of the placeholders in the top of the structure.txt-file?

You open the same file twice:


public static void WriteToFile(string filePath)
{
  //create a string array to gather our text file information.

  StreamReader reader = new StreamReader(filePath);
  StreamReader info = new StreamReader("Structure.txt");



because the argument filePath is also "Structure.txt". Why open the same file more than once for the same operation?



StreamReader and StreamWriter implement IDisposable and should be disposed off like:

using (StreamReader reader = new StreamReader(filePath))
using (StreamWriter writer = new StreamWriter("helle.cs"))
{
   ...
}




You shouldn't hardcode string literals in a method but provide them as arguments:

public static void WriteToFile(string inputFile, string outputFile)
{
   ...
}




Instead of:


 while (!reader.EndOfStream)
 {

    temp = reader.ReadLine();



it is better to do:

string line = null;
while ((line = reader.ReadLine()) != null)
{
   ...
}





  StreamWriter writer = new StreamWriter("Hello.cs", true);


you set the append argument to true, but I'm quite sure you mean to overwrite the existing file?