I have seen that we can implement multiple inheritance in ANSI C? As we can create any class like
struct sampleClass {
int size;
struct sampleClass *ptr1;
};
As I tred to create class and want to implement inheritance. Can you give me some idea how to implement that?
It depends what you mean by "implementing inheritance in C".
It has certainly been done with macros, coding guidelines and styles, and struct of function pointers (mimicking virtual method table) and other metadata. A good example comes from GTK with its GObject layer.
I have seen this being done before.
#include "stdio.h"
#define FRUIT_COLOR_RED 1
struct fruit {
char* name;
};
struct apple {
struct fruit base;
int color;
};
void printFruit(struct fruit *f) {
printf(f->name);
}
int main(int argc, char** argv) {
struct apple a;
a.base.name = "apple";
a.color = FRUIT_COLOR_RED;
printFruit((struct fruit*)&a);
return 0;
}
This works because struct fruit is the first member of struct apple and the two structures are aligned in memory.
|-- 4 or 8 bytes(char*) --| => struct fruit in memory
|-- 4 or 8 bytes(char*) --|-- 4 or 8 bytes(int) --| => struct apple in memory
The first 4 or 8 bytes(depending on 32 bit vs 64 bit respectively) are the same length and type so you can cast a struct apple* to a struct fruit* and because they line up in memory, it reads the members of struct fruit.
I don't know if this is good practice and I would avoid it. I love the simplicity of C, but why not use a language that has these constructs built in such as C++.
Too implement Object Orientation features in C is going to mean more lines of code and more maintenance.
Also if the code doesn't build I wrote it now in notepad, but the concept is there. Don't have a C compiler on me at the moment :-(.
