classes containing arrays of class instances

Projects Programming
1

I am stuck on this problem:

This will compile without error:

class Class1 {
public:
Class1(void) {
}
};

class Class2 {
public:
Class1 classArray[5];

Class2(void){}
};

Class2 class2;

void setup() {}
void loop() {}

but not it will not compile successfully if Class1 contains any instantiation parameters:

class Class1 {
public:
Class1(int a) { // includes instantiation parameter a
}
};

class Class2 {
public:
Class1 classArray[5];

Class2(void){}
};

Class2 class2;

void setup() {}
void loop() {}

I get the following compiler error:

/home/walt/Arduino/arduino_c/class_test/class_test.ino: In constructor 'Class2::Class2()':
class_test:11:17: error: no matching function for call to 'Class1::Class1()'
Class2(void){}

Help, please.

2

Try:

    Class1 classArray[5]={1,2,3,4,5};

There's a warning because class one doesn't use the parameter, but it does compile.

3

Well, that's very interesting! But, I can work with it.

Thank you.

4

Discovered that I can also solve the problem by overloading the Class1 constructor:

class Class1 {
public:
Class1(void) {}
Class1(int a) {}
};

Class1 class1(1);

class Class2 {
public:
Class1 classArray[5];

Class2(void){}
};

Class2 class2;

5

You can indeed. I rather thought that you needed to use the parameterized constructor though.

6

In this case, I want to add to the array on the fly.

I'm working on a variant of Simon Monk's Timer library. I want to work with pre-defined Events and make the timer class interrupt driven..

7

You should probably use initializer lists:

class Class1 {
  public:
    Class1(uint8_t a) : x(a) {          // includes instantiation parameter a
    }
    uint8_t x;
};

class Class2 {
  public:
    Class2(void) : classArray( {
      1, 2, 3, 4, 5
    }) {}
    Class1 classArray[5];

};

Class2 class2;

void setup() {}
void loop() {}

OR:

class Class1 {
  public:
    Class1(uint8_t a) : x(a) {          // includes instantiation parameter a
    }
    uint8_t x;
};

class Class2 {
  public:
    Class2(uint8_t a, uint8_t b, uint8_t c, uint8_t d, uint8_t e) : classArray( {
      a, b, c, d, e
    }) {}
    Class1 classArray[5];

};

Class2 class2(1, 2, 3, 4, 5);

void setup() {}
void loop() {}
8

Thanks. I was not familiar with the use of initializer lists.

That is the fun of this. Even after 40 years of programming, there is still plenty to be learned/discovered.