Unlike python or Java C/C++ splits its files

Why do we do this??

In C++ we can’t use a function until we have defined it

EX:

  int main(){
	printf("%d\n" funnyNumber()); // this wont work
}

int funnyNumber(){
	return 69;
}

To fix this we use forward declaration

  int funnyNumber(); // forward declaration

int main(){
	printf("%d\n" funnyNumber()); // this wont work
}

int funnyNumber(){
	return 69;
}

we say “Hey C++ here I promise I will eventually define this function funnyNumber but don’t freak out when you see it”

Here is a link that goes more in depth: https://www.learncpp.com/cpp-tutorial/classes-and-header-files/

.h file (header file) is like we deleted the body of the function

ILoveBen.h

  int ILoveBen();

ILoveBen.cpp

  #include "ILoveBen.h"
int ILoveBen(){
    return 10;
}

main.cpp

  #include "ILoveBen.h"

int main(){
    printf("%d\\n",ILoveBen());
}

Classes in header files example:

TODO explain y classes have a :: in .cpp file

Ilk.h:

  
class Ilk
{
private:
    int milk;
    int private_func();

public:
    Ilk(int milk);
    ~Ilk();
    void drink(int galOfPilk);
    int getMilk();
};

Ilk.cpp:

  #include "Ilk.h"


int Ilk::private_func() {
    return 69;
}

Ilk::Ilk(int milk) {
    this->milk = milk;
}
Ilk::~Ilk() {}

void Ilk::drink(int galOfPilk) {
    printf("drinking %dL of PILK\n", galOfPilk);
    printf("%d\n", this->private_func());
}
int Ilk::getMilk() {
    return this->milk;
}

main.cpp:

  #include "Ilk.h"


int main() {
    Ilk *i = new Ilk(420);
    printf("%d\n",i->getMilk());
}

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Note: .h == .hpp (these are the same)