仅获取列表中的最后一项

Question

I'm trying to return all data from a list that has more than 30 items. For some reason my code is only giving me the list's last item. I'm sure this is a simple fix but if anyone could help me out that would be great. Here's the code.

List<string> propnumList = new List<string>();
foreach (DataRow drRow in ds7.Tables[0].Rows)
{
    for (int i = 0; i < ds7.Tables[0].Columns.Count; i++)
    {
        propnumList.Add(drRow[i].ToString());
    }
}

using (StreamWriter sw = new StreamWriter("propnumList.txt"))
{
    foreach (string s in propnumList)
    {
        sw.WriteLine(s);
    }
}

string tempProp = "";
foreach (string x in propnumList)
{
    if (x.Length < 30)
    {
        x.Equals(null);
    }
    else
    {
        tempProp = x.Substring(31);
        using (StreamWriter write = new StreamWriter("PROPNUMTEST.txt"))
        {
            write.WriteLine(tempProp); WANT TO RETURN MORE THAN JUST LAST ITEM
        }
    }
}

Answer 1

You are overwriting your output file on each iteration. Place file opening outside the foreach.

using (StreamWriter write = new StreamWriter("PROPNUMTEST.txt"))
{
   foreach (string x in propnumList)
   {
     ....
   }
}