Declare variable as Interface vs. Class

trinh nguyen

Hi, Could anyone explain me the difference between interface and class variable. E.g.: ISomething ivar; //interface variable CSomething cvar; //class variable or IList<MyClass> var1; List<MyClass> var2; I am so confused the difference among them. Thanks in advance!

DaveyM69

Using an interface makes it simpler to use multiple varying class instances that implement an interface without the need for extra coding as the interface defines properties, methods and events that must be accessible.

Dave
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Abhinav S

Technically, there is little to no difference, you would need to instantiate both these variables. However, by defining var1 as an interface type, you have left the actual definition open for later, giving additional flexibility. Based on some options, you could switch between different types at runtime when using an IList. For e.g.

if (flag)
{
var1 = new List();
}
else
{
var 1 = new MyOwnList(); //a custom implementation of IList.
}

Build your own survey - http://www.factile.net

Abhinav S

Technically, there is little to no difference, you would need to instantiate both these variables. However, by defining var1 as an interface type, you have left the actual definition open for later, giving additional flexibility. Based on some options, you could switch between different types at runtime when using an IList. For e.g.

if (flag)
{
var1 = new List();
}
else
{
var 1 = new MyOwnList(); //a custom implementation of the IList interface.
}

Build your own survey - http://www.factile.net