C# Exception Handling

Question

I have class that predominately consists of gather string input and then subsequently outputting the data in a certain format. The result of the class is basically a ToString() override.

With my class I have a static method string Print(string path) that reads the inputs from a flat file. It then parses these inputs and generates an instance of a class for each record in the flat file. Then for each instance of the class I call the class.ToString() and append it to the stringbuilder that eventually gets returned within Print().

I ensure that each record has the necessary values and have appropriate range, if they do not I need to throw an exception. I've never done exception handling before so I want to know if what I want to do is even possible.

When an exception case gets thrown, I want to take whatever is in the stringbuilder add the closing tag cleanup stuff and then prepend the exception text to the stringbuilder and then return (Exception Error Text + stringbuilder.ToString() + FooterStuff).

Edit Code:

It might not actually be a good idea to throw an exception, I might just need to use a try{} catch {} to catch an exception and then append the exception.message to the beginning of the stringbuilder. I don't really know though, exceptions are fairly new to me.

public class Record
{
    public string Name;
    public string Value;
    ...

    private Dictionary<string, LogFormat> = new LogFormat.Table();

    public static string Print()
    {
          Stringbuilder sb = new StringBuilder();
          var k = ReadLog();

          foreach (var x in k)
          {
               sb.Append(x.ToString());
          }

          return sb.ToString();
    }

    public override string ToString()
    {
        if (Table[Name].NeedsValue && (Value == String.Empty || Value == null))
        {
            throw new Exception();
        }

        return String.Format(Table[Name].Format, Attribute, Value);
    }
}

public class LogFormat
{
     public string Format;
     public bool NeedsValue = false;

     public Dictionary<string,LogFormat> Table()
     {
           Dictionary<string,LogFormat> dct = new Dictionary<string,LogFormat>();
           dct.Add("Address", new LogFormat(){Format = "Street:{0}\nCity:{1}"});
           ...
           return dct;
     }
}

Answer 1

I'm not totally sure what you want to achieve but it sounds like you want to use finally

http://msdn.microsoft.com/en-us/library/zwc8s4fz(VS.71).aspx

Answer 2

You need to use a try catch block. See this reference.

You can do the cleanup tasks you need in the catch and finally blocks.

Answer 3

in your class you can use throw statement if something is wrong with your class. And then when you working with you class you should use try-catch-finally block

Answer 4

You can try something like that:

private string YourMethod()
{
    var sb = new StringBuilder();

    try
    {
        // Do your stuff
    }
    catch (ASpecificException ex)
    {
        sb.Insert(0, ex.Message);
    }
    finally
    {
        sb.Append("YourFooter");
    }

    return sb.ToString();
}