Why does "interface have no implementation"? - C# -

Why does "interface have no implementation"? - C# -

i have been reading code theory related multiple inheritance , interfaces. said in places interface class without implementation.

1) utilize of not having implemented methods/functions in interface? back upwards multiple implementations of same method in different classes inherit interface?

2) of code samples out there seem show void interface methods. interface functions/methods void?

to question 1: yes, 1 reason utilize interfaces. interfaces used api component. actual implementation can unknown consumer, supporting loose coupling , testability through unit tests.

regarding question 2: no, interface methods can have same method signatures class methods.

c# interface implementation