string pathDesktop = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
string filePath = pathDesktop + "\\mycsvfile.csv";
string delimter = ",";
string a = "Enoelpro---[037,033,0,018,030,012,004,021,009,038,035,053,044,050,074,F,018,010,070,000]<Vulpix>[-][037,034,0,022,020,029,002,008,024,036,046,049,041,057,077,F,018,005,070,000]<Vulpix>[-] cual es mejor??";
List<string> test = conv(a,"testrainer");
int length = test.Count;
using (TextWriter writer = File.CreateText(filePath))
for (int index = 0; index < length; index++)
This method is equivalent to the StreamWriter(String, Boolean) constructor overload with the append parameter set to false. If the file specified by path does not exist, it is created. If the file does exist, its contents are overwritten. Additional threads are permitted to read the file while it is open.
Here second parameter, true to append data to the file; false to overwrite the file.
If you check the documentation for each method it cleary say the answers for your questions and also there is a suggetion in case of you need to append the file. Use StreamWriter constructor with path and append parameter (true)