Declaring DoubleSolonoid
 

I have been trying to get solenoids to work all day, everything I try kicks back an error

grabSolenoid = new DoubleSolenoid(1, 1, 1);

always says "grabSolenoid is not a class"

What is the proper way to declare and run double solenoids? The screensteps isn't helping.

Re: Declaring DoubleSolonoid
 

Try:

DoubleSolenoid grabSolenoid = new DoubleSolenoid(1, 1, 1);

Re: Declaring DoubleSolonoid
 

Could not convert '(operator new(104u), (<statement>, ((DoubleSolenoid*) <anonymous>)))' from' 'DoubleSolenoid*' to 'DoubleSolenoid'

Re: Declaring DoubleSolonoid
 

Oh, yeah, C++ forum...try:

DoubleSolenoid *grabSolenoid = new DoubleSolenoid(1, 1, 1);

Re: Declaring DoubleSolonoid
 

Oops, my bad... The syntax is almost identical between java and c++, expert for that annoying *. I really hate dealing with punters in c++!

They issue you were having was that you hadn't declared your variable before assuming it, so the compiler didn't know what "grabSolenoid" was. By adding the class in front, you're telling the compiler what that is.

Re: Declaring DoubleSolonoid
 

Here is a bit of explenation.

Could not convert '(operator new(104u), (<statement>, ((DoubleSolenoid*) <anonymous>)))' from' 'DoubleSolenoid*' to 'DoubleSolenoid'

The bolded parts are the important notes. Note the asterisk (or 'star') in the from and also note that it is missing in the to.

The new operator creates a new version of the class (DoubleSolenoid here) and returns a pointer to it. The asterisk (or 'star') indicates changes the type of grabSolenoid to a "pointer to DoubleSolenoid", thus making the types on both sides the same.

Pointers are one of the more confusing aspects of C/C++, however they are used everywhere. Remember, the pointer doesn't hold the data, it just points to where it is at. For classes, use the -> operator to access methods and fields from the pointer.

Re: Declaring DoubleSolonoid
 

Thanks, they do declare now, however...


I really don't understand these pointers, when I try to set the solenoids using something like

grabSolenoid.set(DoubleSolenoid::kForward);

it says "request for member 'set' in '(((Robot*)this))->Robot::grabSolenoid', which is of pointer type 'DoubleSolenoid' (maybe you meant to use '->' ?)"

where do I put the ->?

Re: Declaring DoubleSolonoid
 

Try grabSolenoid->Set(DoubleSolenoid::kForward);

Re: Declaring DoubleSolonoid
 

You have declared grabSolenoid as a pointer to a double solenoid object. The member functions like Set() only work on an actual object. You need to dereference the pointer before you can call the function. The '->' is a small bit of syntax convenience that lets you dereference the pointer and do the equivalent of a '.' at the same time.

Just replace the '.' with '->' between the variable name and the function name.

Re: Declaring DoubleSolonoid
 

Yes. obj_ptr->elt is equivalent to (*obj_ptr).elt . That is, look up the actual field or method within the object that obj_ptr points to.

Re: Declaring DoubleSolonoid
 

Once you get the syntax correct, you'll want to make sure you're allocating unique channels, as you'll likely get a runtime error as written.

Re: Declaring DoubleSolonoid
 

Well it seems to have worked, I cant test it yet on actual solenoids, but it builds and deploys just fine