In C#, as operator is like a cast operation, which performs only reference conversion, nullable conversion and boxing conversion. as keyword can not be perform to other conversion such as user define conversion.
Example
using System;
namespace as_keyword_in_c_sharp
{
class c1 // create class c1
{
}
class c2 //create another class c2,which is return type is string
{
public string show(string str)
{
return str;
}
}
class Program
{
static void Main(string[] args)
{
c1 obj1 = new c1(); //create object of class c1
c2 obj2 = new c2(); //create object of class c2
object[] obj_array = new object[6]; //create object type array
object a= 123; //create object type variable, which is value is int type
object b = "welcome"; //create object type variable, which is value is string type
object c = 10.05; //create object type variable, which is value is double type
object d = null; //create object type variable, which is value is null type
//store object type value in object type array
obj_array[0] = obj1;
obj_array[1] = obj2.show("hello");
obj_array[2] = a;
obj_array[3] = b;
obj_array[4] = c;
obj_array[5] = d;
for (int k = 0; k < obj_array.Length; k++)
{
Console.Write(" {0} : ", k);
// conversion of object type value to string type through as keyword
string str = obj_array[k] as string;
if (str != null)
{
Console.WriteLine("'" + str + "'");
}
else
{
Console.WriteLine("No string");
}
}
Console.ReadLine();
}
}
}
Output
Ammar ShaukatPosted Mar 14, 2017, 2:41 AM
As keyword use to cast the types explicitly. The only difference between a regular cast and "as" is that , you perform regular cast when you are sure about the types which are being casted. and when you are not sure about the types , either they are same or not , then better to use "as" keyword to safely perform the operation