how to return null instead of object?

Projects Programming
1

Hi,

I have an array of object RCStickAxis called myAxes..
I have a function which should return a single element of it, taking the id as argument.
I want to check for indexOutOfBounds. If I am out of bounds, I want to return null, otherwise I want to return the myAxis element.

I have following function in a class:

RCStickAxis RCStick::getAxis(unsigned char axis)
{
 // check bounds
 if (axis >=0 && axis < sizeof (myAxes))
 {
 // we are in bounds
 return myAxes[axis];
 }
 else
 {
 Log.fatal(F("RCStick::getAxis(unsigned char axis) requests stick which is out of bounds. Requested: %d, valid is 0 to %d. Returning NULL!\n"), axis, sizeof(myAxes)-1);
 return NULL;
 }
}

When trying to compile I get following error:

..\RCStick.cpp:33:10: error: could not convert '0' from 'int' to 'RCStickAxis'
 return NULL;
        ^
subdir.mk:34: recipe for target 'RCStick.cpp.o' failed
make: *** [RCStick.cpp.o] Error 1

What am I doing wrong or how do I implement it better? Try catch around the call from the outside?

Thanks, Andreas

3

If 'myAxes' is an array of 'RCStickAxis' object aka pointers you can use 'nullptr'.

4

@butch: After 23 posts you should know how to use code tags when posting source code. If not, please read the first four posts at the top of this Forum.