In your method setDetails you haven’t specified anything for the return type, if it is not returning anything then specify void For Voter class for Candidates class One other thing, (Thanks to Frank Pavageau) your class name is Candidates and you have defined the constructor with Candidate without s, that is why it is being considered as a normal method, and thus should have a return type. You your rename … Read more
On a Java OOP project I got three errors on my constructor: .\Voter.java:14: error: invalid method declaration; return type required .\Candidates.java:7: error: invalid method declaration; return type required .\Candidates.java:14: error: invalid method declaration; return type required codes for constructor: i declared my constructors like this: Anything I missed?
If you think about the Greek roots of the term, it should become obvious. Poly = many: polygon = many-sided, polystyrene = many styrenes (a), polyglot = many languages, and so on. Morph = change or form: morphology = study of biological form, Morpheus = the Greek god of dreams able to take any form. So … Read more
Variables declared inside the class definition, but not inside a method are class or static variables: As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have This is different from C++ and Java, but not so different from C#, where a static member can’t be accessed using … Read more
What the inFile >> S does is take in the file stream, which is the data in you file, and uses a space delimiter (breaks it up by whitespace) and puts the contents in the variable S. For example: If we had a file that had the follow contents and we used inFile >> S with our file: we … Read more
As mentioned by other here: Interfaces are not necessary in Python. This is because Python has proper multiple inheritance, and also ducktyping, which means that the places where you must have interfaces in Java, you don’t have to have them in Python. That said, there are still several uses for interfaces. Some of them are covered by … Read more
A function is a piece of code that is called by name. It can be passed data to operate on (i.e. the parameters) and can optionally return data (the return value). All data that is passed to a function is explicitly passed. A method is a piece of code that is called by a name that is associated with … Read more
Private members are only accessible within the class defining them. Protected members are accessible in the class that defines them and in classes that inherit from that class. Edit: Both are also accessible by friends of their class, and in the case of protected members, by friends of their derived classes. Edit 2: Use whatever … Read more
They are absolutely different. Inheritance is an “is-a” relationship. Composition is a “has-a”. You do composition by having an instance of another class C as a field of your class, instead of extending C. A good example where composition would’ve been a lot better than inheritance is java.util.Stack, which currently extends java.util.Vector. This is now … Read more
What are you using to compile this? If there’s an undefined reference error, usually it’s because the .o file (which gets created from the .cpp file) doesn’t exist and your compiler/build system is not able to link it. Also, in your card.cpp, the function should be Card::Card() instead of void Card. The Card:: is scoping; … Read more