C# 循环遍历文件

Question

I am trying to parse.msg files using an MSGReader library and while it works for single files, the moment I try to do it as a loop, nothing works anymore. My code is hideous as I couldn't find a way to grab specific lines from a multiline string, but it works without the loop.

What am I doing wrong here?

private void btfolder_Click(object sender, EventArgs e)
{
    if (folderBrowserDialog1.ShowDialog() == DialogResult.OK);
    
    foreach (var file in Directory.EnumerateFiles(folderBrowserDialog1.SelectedPath, "*.msg"))
    {
        using (var msg = new MsgReader.Outlook.Storage.Message(file))
        {                    
            var htmlBody = msg.BodyHtml;
            
            tbbody.Text = htmlBody;
            string who = tbbody.Lines[42];
            string error = tbbody.Lines[46];
            who = who.Substring(3, who.Length - 7);
            error = error.Substring(0, error.Length - 7);
            tbsender.Text = who;
            tberror.Text = error;

            DataTable dts = new DataTable();
            DataTable dt = new DataTable();
            dts.Columns.Add("Absender", typeof(string));
            dts.Columns.Add("error", typeof(string));
            dts.Rows.Add(who, error);
            dt.Merge(dts);
            dgvemail.DataSource = dt;
        }
    }
}

I expected the code to cycle through all 9.msg files, update my textboxes and populate my data.table.

Instead I get: "startIndex cannot be larger than the length of string. Arg_ParamName_Name"

Answer 1

You can't just assume the length of values, you need to verify that the starting points are correct:

//Theres no guarentee you can do any of these:
string who = tbbody.Lines[42];
string error = tbbody.Lines[46];
who = who.Substring(3, who.Length - 7);
error = error.Substring(0, error.Length - 7);

Try validating the message first. or atleast cheching the length

Note: this is ugly and you should figure out a way to valid based on the message format

if(tbbody.lines.length < 47) {
    continue;
}
string who = tbbody.Lines[42];
string error = tbbody.Lines[46];


if(who.length < 11) {
   continue;
}
who = who.Substring(3, who.Length - 7);

if(error.length < 8) {
   continue;
}
error = error.Substring(0, error.Length - 7);