Why the someFunc() has obj as parameter but not &obj in the main .

Answer 1

This is called passing by reference.
While calling the method inside main() you just pass the argument to it and in the actual method definition you use a reference of that argument as a parameter by preceding it with &.

In this way you do not create a copy of the argument but get the reference and make modifications.

So any modifications made inside the method will be reflected to the one inside the main().

Answer 2

class MyClass {
public:
MyClass() {
regvar = 0;
}
private:
int regVar;

friend void someFunc(MyClass &obj);
};

void someFunc(MyClass &obj) {
obj.regVar = 42;
cout << obj.regVar;
}
Int main(){
Myclass obj;
SomeFunc(obj);

}
//outputs : 42

Answer 3

If you are talking about passing a var by address
Then it will be like this

Type SomeFun(type *Name)

Then in main()
SomeFun(&SomeVar)

*This is C++ format

Answer 4

Mention the language and share the piece of code that you do not understand.

Answer 5

Please clear your question