1 　　string[] fileNameX = Directory.GetFiles(@"D:\Sjdc", "*.xls?");
2 　　Array array = Array.CreateInstance(typeof(string),fileNameX.Length);
3 　　fileNameX.CopyTo(array, 0);

 1 　　　　　　　string[] fileNameX = Directory.GetFiles(@"D:\Sjdc", "*.*");
 2             List<string> lists = new List<string>();
 3             for (int i = 0; i < fileNameX.Length; i++)
 4             {
 5                 string fileNamei = fileNameX[i].ToLower();
 6                 if (fileNamei.EndsWith(".xls") || fileNamei.EndsWith(".xlsx"))
 7                 {
 8                     lists.Add(fileNamei);
 9                 }
10             }
11             Array array = Array.CreateInstance(typeof(string), lists.Count);
12             lists.CopyTo((string[])array, 0);

1 　　　　　　 var  files = Directory.GetFiles(@"D:\Sjdc", "*.*", SearchOption.AllDirectories).Where(s => s.EndsWith(".XLSX") || s.EndsWith(".XLS"));
2            List<string> listFile = new List<string>();
3            foreach (string s in files)
4            {
5                listFile.Add(s);
6            }