QuantumLeaps / OOP-in-C

Simple and memory-efficient implementation of OOP in C suitable for real-time embedded systems.

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Object-Oriented Programming in C

This repository provides the code accompanying the article (as well as videos): "Object-Oriented Programming in C". The code can be compiled and executed on any desktop computer (running Windows, Linux, or macOS), although it is also suitable for real-time embedded applications.

Videos

The concepts of OOP in C have been explained in a series of videos:

Object-Oriented Programming in C Playlist

• OOP part-1 "Encapsulation"
• OOP part-2 "Inheritance"
• OOP part-3 "Poylmorphism in C++"
• OOP part-4 "Polymorphism in C"

Quick Example

Here is a class Shape in portable ISO-compliant C (e.g., for displaying shapes on a LCD):

// file shape.h

// Shape's attributes...
typedef struct {
    int16_t x; // x-coordinate of Shape's position
    int16_t y; // y-coordinate of Shape's position
} Shape;

// Shape's operations (Shape's interface)...
void Shape_ctor(Shape * const me, int16_t x, int16_t y);
void Shape_moveBy(Shape * const me, int16_t dx, int16_t dy);
int16_t Shape_getX(Shape const * const me);
int16_t Shape_getY(Shape const * const me);

And here are some examples of using the Shape class:

#include "shape.h"  // Shape class interface
#include <stdio.h>  // for printf()
. . .

Shape s1; // instances of Shape (object)
Shape s2; // another instance of Shape (object)

Shape_ctor(&s1, 0, 1);
Shape_ctor(&s2, -1, 2);

printf("Shape s1(x=%d,y=%d)\n", Shape_getX(&s1), Shape_getY(&s1));
printf("Shape s2(x=%d,y=%d)\n", Shape_getX(&s2), Shape_getY(&s2));

Shape_moveBy(&s1, 2, -4);
Shape_moveBy(&s2, 1, -2);

printf("Shape s1(x=%d,y=%d)\n", Shape_getX(&s1), Shape_getY(&s1));
printf("Shape s2(x=%d,y=%d)\n", Shape_getX(&s2), Shape_getY(&s2));

Code Organization

OOP-in-C/
+---doc/
¦       AN_OOP_in_C.pdf
¦
+---encapsulation/
¦       main.c
¦       make.bat
¦       shape.c
¦       shape.h
¦
+---inheritance/
¦       main.c
¦       make.bat
¦       rect.c
¦       rect.h
¦       shape.c
¦       shape.h
¦
+---polymorphism/
        circle.c
        circle.h
        main.c
        make.bat
        rect.c
        rect.h
        shape.c
        shape.h

Building and Running the Code

Each of the sub-directories contains make.bat (for Windows) that allows you to build and run the provided examples. (On Linux/macOS you can execute the commands from make.bat directly from the tarminal).

For example:

C:\GitHub\OOP-in-C>cd encapsulation
C:\GitHub\OOP-in-C\encapsulation>make

gcc shape.c main.c -o oop_in_c
oop_in_c

Shape s1(x=0,y=1)
Shape s2(x=-1,y=2)
Shape s1(x=2,y=-3)
Shape s2(x=0,y=0)

The PDF Version

The PDF version of the "Object-Oriented Programming" article is provided in the directory doc

Application Note: OOP in C [PDF]

Licensing

The OOP-in-C source code and examples are released under the terms of the permissive MIT open source license. Please note that the attribution clause in the MIT license requires you to preserve the original copyright notice in all changes and derivate works.

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Contact Information

• state-machine.com
• state-machine.com/oop