four line in textbox save in multiple excel columns c#.net W

hi,
Agree with Muralidharan you can split the the textbox value with Environment.NewLine and process the data.

Try the below code.

             string textBoxContents = textBox1.Text;
            string[] splitter = new string[]{Environment.NewLine};
            string appender = ",";
            string[] allTextLines = textBoxContents.Split(splitter,StringSplitOptions.RemoveEmptyEntries);
            string result = String.Join(appender,allTextLines);
            File.AppendAllText("c:\\temp.csv",result);
If you want more explanations of the above code, please let me know.
You need to open the csv file in excel and you'll get the desired output.