checkElements.cs

ArrayList arList = new ArrayList()
                {
                    1,
                    "Bill",
                    300,
                    4.5f,
                    300
                };

Console.WriteLine(arList.Contains(300)); // true
Console.WriteLine(arList.Contains("Bill")); // true
Console.WriteLine(arList.Contains(10)); // false
Console.WriteLine(arList.Contains("Steve")); // false