object myObject = new Object();

string myObjectString = myObject.ToString();

如果对象不为null并保留字符串值
使用这样的语句-------

if object is not null and hold string value
use statement like this-------

Object obj=new Object();
obj="hi";

string str1=Convert.ToString(obj);
string str2=obj.ToString();
string str3= obj as string;
string str4=(string)obj;