From eqqon

Error Formatting for Visual C#

Today I wrote a nice little debug helper function called PrintException in C#. It prints all available information about an exception and its inner exceptions to the output recursively. The clue is, that it does this in a format that is understood by the error parser of Microsoft Visual Studio. So if you get an exception you can easily navigate to the source locations by clicking on the lines in the printed stacktrace. It also prints inner exceptions recursively with increasing indent, which is extremely useful! Note: Error parser formatting works, of course, only when compiled in debug mode. Also the redirection of standard out to Visual Studio's output window is only activated for a Windows Forms application not for a Console application.

Here is a simple example of usage of Debug.PrintException:

public static class PrintExceptionTest
{
    static void test()
    {
        try { test1(); }
        catch (Exception e) { throw new Exception("outer exception message", e); }
    }

    static void test1()
    {
        throw new InvalidOperationException("inner exception message");
    }

    public static void Main()
    {
        try { test(); }
        catch (Exception e) { Debug.PrintException(e); }
        Console.ReadLine();
    }
}

The output generated by the above example follows. Links to source files are recognized by Visual Studio's error parser. Works also in some other IDEs and editors like Scite:

********************************************************************************
Exception: "outer exception message"
--------------------------------------------------------------------------------
InnerException:
   ********************************************************************************
   InvalidOperationException: "inner exception message"
   --------------------------------------------------------------------------------
     c:\C#\snippets\print_exception.cs(58,1):   PrintExceptionTest.test1()
     c:\C#\snippets\print_exception.cs(48,1):   PrintExceptionTest.test()
   ********************************************************************************
  c:\C#\snippets\print_exception.cs(52,1):   PrintExceptionTest.test()
  c:\C#\snippets\print_exception.cs(65,1):   PrintExceptionTest.Main()
********************************************************************************

And this is the implementation of PrintException:
using System;

public static class Debug
{
    public static void PrintException(Exception exception)
    {
        PrintException(exception, "");
    }

    public static void PrintException(Exception exception, string indent)
    {
        string stars = new string('*', 80);
        Console.WriteLine(indent + stars);
        Console.WriteLine(indent + "{0}: \"{1}\"", exception.GetType().Name, exception.Message);
        Console.WriteLine(indent + new string('-', 80));
        if (exception.InnerException != null)
        {
            Console.WriteLine(indent + "InnerException:");
            PrintException(exception.InnerException, indent + "   ");
        }
        foreach (string line in exception.StackTrace.Split(new string[] { " at " }, StringSplitOptions.RemoveEmptyEntries))
        {
            if (string.IsNullOrEmpty(line.Trim())) continue;
            string[] parts;
            parts = line.Trim().Split(new string[] { " in " }, StringSplitOptions.RemoveEmptyEntries);
            string class_info = parts[0];
            if (parts.Length == 2)
            {
                parts = parts[1].Trim().Split(new string[] { "line" }, StringSplitOptions.RemoveEmptyEntries);
                string src_file = parts[0];
                int line_nr = int.Parse(parts[1]);
                Console.WriteLine(indent + "  {0}({1},1):   {2}", src_file.TrimEnd(':'), line_nr, class_info);
            }
            else
                Console.WriteLine(indent + "  " + class_info);
        }
        Console.WriteLine(indent + stars);
    }
}

Blogged by --Henon 12:07, 9 November 2007 (CET)