关于#Excel#的问题，如何解决？

帮帮忙，写的时候代码没有报错但是运行的时候突然蹦出来这个😭我找不到我的引用有什么错误，有没有帮帮忙，我纯纯的新😭

不是引用错误，是你有变量是null了

看下是不是myApp 为空了

不建议使用这种方式容易出错，可以去nuget下载下面两个包

读取代码
OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory);//注意这里写路径时要用c:\而不是c:
openFileDialog.Filter = "EXCEL文件|.xls|所有文件|.*";
openFileDialog.FilterIndex = 1;
DataTable dt_temp=new DataTable(),dt1;
if (openFileDialog.ShowDialog() == DialogResult.OK)
{
//dt = ExcelRead.ThreadReadExcel(openFileDialog.FileName);
using (var stream = File.Open(openFileDialog.FileName, FileMode.Open, FileAccess.Read))
{
// Auto-detect format, supports:
// - Binary Excel files (2.0-2003 format; *.xls)
// - OpenXml Excel files (2007 format; *.xlsx, *.xlsb)
using (var reader = ExcelReaderFactory.CreateReader(stream))
{
var result = reader.AsDataSet();
// The result of each spreadsheet is in result.Tables
dt_temp = result.Tables[0];
}
}
}

        //dt_temp.Columns.Remove("列名称");
        for (int i = dt_temp.Columns.Count - 1; i > 13; i--)
        { dt_temp.Columns.RemoveAt(i); }