String.Join函数

 string[] str1 = { "abc", "bcd", "cde", "efg" };
 string str2 = string.Join(",", str1);
 string str3 = string.Join("_", str1);
 Console.WriteLine("str2: {0}\nstr3: {1}" , str2, str3);
 Console.ReadKey();

输出结果：