How to call a template class method?

Question

i've just learned class templates and have began to experiment with them, but the question is: how to i call them correctly? i keep getting three errors:

-could not deduce template argument for 'A'
-expects 0 arguments - 1 provided
- no instance of function template "calculator<C>::addition [with C=int]" matches the argument list

my source code:
https://code.sololearn.com/cgTc8vXvfHG8

Answer 1

If you had just used the type C everywhere, it would have been fine.

But you have used templates further in your class methods, and plus,you have used different names.

Thus, the compiler expects that it is to return a new type and this type must be specified by you before use of that function.

So, to call operation :

user.operation<int>().

And now you may use the returned value.

But, since the type O may not be equal to A,S,M or D in the operations, you will have to change your function calls to:

cout<<"The sum of the two numbers is - "<<addition<O>()<<endl;
And so on for the others.

And Don't forget the braces after the <O>. ( '(' & ')' )

Thus, you need to pass the type O to the arguments A,S,M and D of the templates, as it is no longer possible to determine these implicitly.