default keyword in c#

The “Default” keyword in c# can be used in the following scenarios .

The main use of default comes in to picture when used in the generic code.

1. To return Type’s Default Value

The Default returns the type’s default value.

For the Integer , it returns 0 , for Boolean , it returns false and for the reference types , it returns null

int valueI = default(Int32);

bool ValueB = default(Boolean);

string senthil = default(String);

MessageBox.Show(valueI.ToString()) ;// "0"

MessageBox.Show(ValueB.ToString()); // "False"

MessageBox.Show(senthil); // nothings

There is another way to get the default value via the following example.

int ValueI = new int();

Here ValueI will be 0 .


2. The keyword default is used within the switch case block to take the default value if nothing is found .

int i =0 ;

switch (i)

{

     case 1 :

               MessageBox.Show("1");

               break;

     case 2 :

               MessageBox.Show("2");

               break;

     case 3:

               MessageBox.Show("3");

               break;

     default:

               MessageBox.Show("Default");

}


3. To know , if the type is a Reference or  Value type

if (default(T) == null)
    MessageBox.Show("Reference Type");
else
    MessageBox.Show("Value Type");
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6 thoughts on “default keyword in c#

  1. Pingback: Tweets that mention Default keyword in c# | Ginktage -- Topsy.com

  2. #3: The System.Type class does have an IsValueType property, so instead of doing this, a better solution would be:

    if (typeof(T).IsValueType)

  3. Pingback: default keyword in c# | ProgramInDotnet

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