Hi there. Not a total newbie to programming, but a newbie to C and variants. (Extensive VB experience from 25 years ago).
I'm trying to get a handle on the class / object thing and so I've take the "Morse" 'make a library' tutorial and simplified it to show my problem/question.
I can (and did) paste the class definition (the .h part)and the constructor and methods (the .cpp part) from the Morse tutorial into a simple 'one tab' sketch and of course it works fine. I then removed most of it to 'dumb' it down into just a 'blink' program (left the 'dot' method). Still works of course.
Next I hard coded the pin number into the "pinMode()" and "digitalWrite() functions so I could get rid of the "int pin" parameter/argument that is handed off. (Remember, I'm doing this to demonstrate my issue ... not because I think it's great programming habit).
So here's my problem. Even though the sketch no longer needs to hand off any parameter / argument to the instantiated object for it to function, when I remove the parameter (the 'int pin' part) I can't get it to compile (various errors depending ...).
Here's the code -- I've posted it in runnable form, with the three changes noted which remove the parameters / arguments and supply the errors commented out.
(this is my first post and first time posting code -- I ran auto-format on the code before copying it, but I've no experience to know if it's going to format properly in the post)
// Class Definition:
class Morse
{
public: // Change #1
Morse(int pin); // WORKS
//Morse(); // DOESN'T WORK
void dot();
};
//***********************************
//***********************************
// Constructor: // Change #2
Morse::Morse(int pin) // WORKS
//Morse::Morse() // DOESN'T WORK
{
// I don't need anything done inbetween these brackets,
// but if I remove them I get an error so I leave them.
}
//Method:
void Morse::dot()
{
digitalWrite(13, HIGH);
delay(200);
digitalWrite(13, LOW);
delay(200);
}
//***********************************
//***********************************
//Instantiate: // Change #3
Morse morse(13); // WORKS
//Morse morse(); // DOESN'T WORK
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
morse.dot();
}
Any suggestions? I'm simply trying to learn how to define and instantiate the simplest form of class/object/methods -- one without any parameters passed or returned. I can't seem to find a single example of this so I've been left to try to figure it out by trial and error.
So, you can't get it to compile, because you get "various errors". But, you didn't bother to tell us WHAT errors? Don't you think that information might be helpful to anyone trying to help you find your problem?
RayLivingston:
So, you can't get it to compile, because you get "various errors". But, you didn't bother to tell us WHAT errors? Don't you think that information might be helpful to anyone trying to help you find your problem?
Regards,
Ray L.
Actually, since there are three places in the code this issue is referenced (declaration, instantiation, method call) and there are at least 4 different ways to write those lines (void with brackets, void without brackets, brackets no void, no void no brackets) the number of combinations is such that had I posted the full code to each option (as you would have undoubtedly requested) with the error messages associated, I suspect your response would have been just as critical of me for clogging up a post with so many 'wrong' code examples.
You may not like it, but my choice was thought out carefully in an attempt to explain the problem without making people wade through bad example after bad example after bad example after bad example after bad example after bad example after bad example after bad example(see?).
I'll repeat my problem ... I can't figure out (nor find an example) of declaring, instantiating and utilizing a simple class / object / method -- one that does not involve declaring/passing any parameters/arguments. I can show you a hundred ways that don't work. I'm looking to be pointed towards one that does.
Morse::Morse(int pin) // WORKS
{
Serial.print("CONSTRUCTOR WITH PIN ");
Serial.println(pin);
} // WORKS
Morse::Morse() // DOESN'T WORK
{ Serial.println("DEFAULT CONSTRUCTOR");} // DOESN'T WORK
void setup() {
Serial.begin(115200);
Serial.println("Morse test");
Morse m, M1(10);
}
void loop() {}
a run gives
Morse test
DEFAULT CONSTRUCTOR
CONSTRUCTOR WITH PIN 10
Thanks Horace. I appreciate your efforts with the sample sketch, but unfortunately it doesn't get me any closer to answering my question .... in your declaration you are still including 'int pin' as a parameter and I'm specifically attempting to declare, instantiate and utilize the simplest possible form of class/object/method -- one that does not pass any arguments.
// Class Definition:
class Morse
{
public: // Change #1
Morse(int pin); // WORKS
Morse(); // DOESN'T WORK
void dot();
};
//***********************************
//***********************************
// Constructor: // Change #2
Morse::Morse(int pin) // WORKS
{}
Morse::Morse() // DOESN'T WORK
{
// I don't need anything done inbetween these brackets,
// but if I remove them I get an error so I leave them.
}
//Instantiate: // Change #3
Morse morse(13); // WORKS
Morse morse1; // DOESN'T WORK
Morse morse2();
you also also named both objects morse I changed the second to morse1 - note that morse2() also works
Following is a link to the tutorial, but please let's not get the thread off track too much inside the tutorial. My question is not related to the tutorial -- I merely pasted some simply and working code from it as a starting point. My question is about something that is not done nor addressed in the tutorial.
aarg:
Can you supply the actual code that exhibits the problem then?
As I replied to RayLivingston above, there are countless versions I have coded that exhibit the problem and I posted one of them in my initial post.
In the code I posted, I even tried made it easy for someone to toggle back and forth between working code and non-working code (just switch out the short "WORKS" lines with the "DOESN'T WORK" lines.
If you really need more than one non-working way to write the sketch, let me know -- I have lots of them.
aarg, here is the snippet from my original post, toggled into the non-working state.
Thanks
JB
// Class Definition:
class Morse
{
public: // Change #1
//Morse(int pin); // WORKS
Morse; // DOESN'T WORK
void dot();
};
//***********************************
//***********************************
// Constructor: // Change #2
//Morse::Morse(int pin) // WORKS
Morse::Morse // DOESN'T WORK
{
// I don't need anything done inbetween these brackets,
// but if I remove them I get an error so I leave them.
}
//Method:
void Morse::dot()
{
digitalWrite(13, HIGH);
delay(200);
digitalWrite(13, LOW);
delay(200);
}
//***********************************
//***********************************
//Instantiate: // Change #3
//Morse morse(13); // WORKS
Morse morse; // DOESN'T WORK
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
morse.dot();
}
gfvalvo, thanks for your reply and suggestion of removing the brackets entirely. Your explanation makes sense to me.
As I mentioned above, I had tried that previously to no avail. Following is the non-working code snipped with the brackets removed per your suggestion.
Thanks
JB
// Class Definition:
class Morse
{
public:
Morse;
void dot();
};
//***********************************
//***********************************
// Constructor:
Morse::Morse
{
// I don't need anything done inbetween these brackets,
// but if I remove them I get an error so I leave them.
}
//Method:
void Morse::dot()
{
digitalWrite(13, HIGH);
delay(200);
digitalWrite(13, LOW);
delay(200);
}
//***********************************
//***********************************
//Instantiate:
Morse morse;
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
morse1.dot();
}
// Class Definition:
class Morse
{
public:
Morse();
void dot();
};
// Constructor:
Morse::Morse()
{
// I don't need anything done inbetween these brackets,
// but if I remove them I get an error so I leave them.
}
//Method:
void Morse::dot()
{
digitalWrite(13, HIGH);
delay(200);
digitalWrite(13, LOW);
delay(200);
}
//Instantiate:
Morse morse1;
void setup()
{
pinMode(13, OUTPUT);
}
void loop()
{
morse1.dot();
}
I removed all reference to the default constructor because the compiler provides it. You can override it if you need it to initialize something, but since you don't, just leave it out. Note that pin thirteen didn't flash on my board so I had to change it to a hardwired led.
