What will happen,if we compile below code in C#?

private int sum(int a, int b)
{
try
{
}
catch (Exception ex)
{
throw ex;
}
}

It will throw an error at compile time saying that :-
"not all code paths return a value". Meaning that once we create a function having return type then, it must be returned from function.

So,in above function return type is Integer,so we must return any Integer value from method then it will compile.