Is and As Operator in C#

What are Is and As Operators?

In C#, the is and as operators are used to test and convert types in a safe manner. These operators help check object types at runtime and perform type conversions without throwing exceptions.

Is Operator

The is operator checks if an object is of a certain type and returns true if it is, otherwise false. It is useful for performing type checks before casting objects.

Example: Using the Is Operator

object obj = "Hello, C#";

if (obj is string)
{
    Console.WriteLine("obj is a string");
}
else
{
    Console.WriteLine("obj is not a string");
}
        

In this example, the is operator is used to check if obj is of type string. If true, it prints "obj is a string".

As Operator

The as operator is used to safely cast an object to a specific type. If the object is compatible with the specified type, it returns the object cast to that type. Otherwise, it returns null instead of throwing an exception.

Example: Using the As Operator

object obj = "Hello, C#";

string str = obj as string;
if (str != null)
{
    Console.WriteLine("obj was cast to a string: " + str);
}
else
{
    Console.WriteLine("obj is not a string");
}
        

In this example, the as operator attempts to cast obj to a string. If the cast is successful, it prints the string; otherwise, it returns null.

Difference Between Is and As Operators

While both is and as operators deal with type checking and casting, they have key differences:

Key Points to Remember

• The is operator checks if an object is of a specified type and returns true or false.
• The as operator attempts to cast an object to a specified type and returns null if the cast is not possible.
• Use is when you want to check the type of an object without casting it.
• Use as when you need to perform a safe cast that won't throw an exception if it fails.