Implemented Bresenham's Algorithm in C++.

C++/Bresenham/Makefile

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+CXX = g++
+# Update these paths to match your installation
+# You may also need to update the linker option rpath, which sets where to look for
+# the SDL2 libraries at runtime to match your install
+SDL_LIB = -L/usr/local/lib -lSDL2 -Wl,-rpath=/usr/local/lib
+SDL_INCLUDE = -I/usr/local/include
+CXXFLAGS = -Wall -c -std=c++14 $(SDL_INCLUDE)
+LDFLAGS = $(SDL_LIB)
+EXE = circle
+
+all: $(EXE)
+
+
+$(EXE): circle.o
+
+	$(CXX) $< $(LDFLAGS) -o $@
+
+main.o: circle.cpp
+
+	$(CXX) $(CXXFLAGS) $< -o $@
+
+clean:
+
+	rm *.o && rm $(EXE)

C++/Bresenham/README.md

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+# Bresenham's Algorithm to draw a circle
+
+## Requirements
+This implementation uses SDL 2 to draw the circle on a separate window. So, make sure your system has SDL 2 installed before you run.
+
+## How to run
+This project has an associated makefile. Just run make to build the project and run ./circle executable.
+
+## About the algorithm
+This implementation is based on this [wikipedia page](https://en.wikipedia.org/wiki/Midpoint_circle_algorithm).

C++/Bresenham/circle.cc

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+/**
+ * Bresenham's Algorithm to draw a circle.
+ *
+ * @author rhythm1705
+ * @version 12 April 2020
+ */
+
+#include <iostream>
+#include <SDL2/SDL.h>
+
+#define WINDOW_SIZE 640 // the lenght and width of the window
+#define RADIUS 150 // the radius of the circle
+
+// Draw point in all octants
+void drawPoints(SDL_Renderer *ren, int xc, int yc, int x, int y) {
+	SDL_RenderDrawPoint(ren, xc + x, yc + y);
+	SDL_RenderDrawPoint(ren, xc - x, yc + y);
+	SDL_RenderDrawPoint(ren, xc + x, yc - y);
+	SDL_RenderDrawPoint(ren, xc - x, yc - y);
+	SDL_RenderDrawPoint(ren, xc + y, yc + x);
+	SDL_RenderDrawPoint(ren, xc - y, yc + x);
+	SDL_RenderDrawPoint(ren, xc + y, yc - x);
+	SDL_RenderDrawPoint(ren, xc - y, yc - x);
+	SDL_RenderPresent(ren);
+	// delay to show animation
+	SDL_Delay(20);
+}
+
+// Calculate radius error
+int radiusError(int x, int y, int r) {
+	return (x * x) + (y * y) - (r * r);
+}
+
+// Bresenham's Algorithm to draw a circle
+void circleBres(SDL_Renderer *ren, int xc, int yc, int r) {
+	int x = r;
+	int y = 0;
+	while (x >= y) {
+		drawPoints(ren, xc, yc, x, y);
+		int decision = 2 * (radiusError(x, y, r) + (2 * y) + 1) + (1 - (2 * x));
+		y++;
+		if (decision > 0) {
+			x--;
+		}
+	}
+}
+
+int main() {
+	SDL_Event event;
+	// initialize SDL video subsystem
+	if (SDL_Init(SDL_INIT_VIDEO) != 0) {
+		std::cout << "SDL_INIT Error: " << SDL_GetError() << std::endl;
+		return 1;
+	}
+	// open a window to draw the circle on
+	SDL_Window *win = SDL_CreateWindow("Circle using Bresenham's Algorithm", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WINDOW_SIZE, WINDOW_SIZE, SDL_WINDOW_SHOWN);
+	if (win == nullptr){
+		std::cout << "SDL_CreateWindow Error: " << SDL_GetError() << std::endl;
+		SDL_Quit();
+		return 1;
+	}
+	// create a renderer to render the circle
+	SDL_Renderer *ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
+	if (ren == nullptr){
+		SDL_DestroyWindow(win);
+		std::cout << "SDL_CreateRenderer Error: " << SDL_GetError() << std::endl;
+		SDL_Quit();
+		return 1;
+	}
+	// set center and radius of circle
+	int xc = WINDOW_SIZE / 2;
+	int yc = WINDOW_SIZE / 2;
+	int r = RADIUS;
+	// set color of circle
+	SDL_SetRenderDrawColor(ren, 255, 0, 0, 255);
+	// draw circle
+	circleBres(ren, xc, yc, r);
+	// quit window on close
+	while (1) {
+		if (SDL_PollEvent(&event) && event.type == SDL_QUIT)
+			break;
+	}
+	SDL_DestroyRenderer(ren);
+	SDL_DestroyWindow(win);
+	SDL_Quit();
+	return 0;
+}