Simple script where you import a txt file to sum together all the number values. In the txt file there is one letter (incorrectly entered) instead of a number.

12.30 14.30 16.30 17.89 y // Incorrect entry

Using try/catch will ensure that I am aware of this mistake.

As a learning exercise how do I still get the exception comment yet still allow the script to continue. To give an output EVENTHOUGH the final total will be wrong?

CodePudding user response：

to capture the exception message in general (ignoring TryParse etc)

  string message = null;
  try
  {
       // do stuf that might throw
  }
  catch(Exception e)
  {
      message = e.Message;
  }
  if (message != null)
  {
      // error happened and we have the message
  }
  else
  {
       // all ok
  }    
     
  

CodePudding user response：

Since this is for learning, I would recommend using TryParse rather than Parse and rather than placing code in the form, use a class as shown next where return information is done with tuples and deconstruct by the caller.

using System;
using System.Collections.Generic;
using System.IO;

namespace YourNamespace
{
    public class Operations
    {
        public static (decimal total, List<int> linesBad, Exception exception) GetTotals(string fileName)
        {
            List<int> badLines = new();
            decimal total = 0;

            try
            {
                using (StreamReader reader = new(fileName))
                {
                    int index = 0;
                    while (!reader.EndOfStream)
                    {
                        if (decimal.TryParse(reader.ReadLine(), out var result))
                        {
                            total  = result;
                        }
                        else
                        {
                            badLines.Add(index);
                        }

                        index  ;
                    }
                }

                return (total, badLines, null);

            }
            catch (Exception ex)
            {
                return (total, badLines, ex);
            }
        }
    }
}

To keep things simple I use a Console app. Using return values use total for your label, badLines if not empty has any line that was not a decimal and exception if there was a runtime exception e.g. missing file.

static void Main(string[] args)
{
    var (total, badLines, exception) = Operations.GetTotals("example.txt");

    if (exception is null)
    {

        Console.WriteLine($"Total: {total:C2}");

        if (badLines.Any())
        {
            Console.WriteLine($"Bad lines: {string.Join(",", badLines)}");
        }

    }
    else
    {
        Console.WriteLine(exception.Message);
    }

    Console.ReadLine();
}