Task: Draw a clock
C: #include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <sys/time.h>
 
#define PI 3.14159265
const char * shades = " .:-*ca&#%@";
 

double dist(double x, double y, double x0, double y0) {
	double l = (x * x0 + y * y0) / (x0 * x0 + y0 * y0);
 
	if (l > 1) {
		x -= x0;
		y -= y0;
	} else if (l >= 0) {
		x -= l * x0;
		y -= l * y0;
	}
	return sqrt(x * x + y * y);
}
 
enum { sec = 0, min, hur }; 
 
void draw(int size)
{
#	define for_i for(int i = 0; i < size; i++)
#	define for_j for(int j = 0; j < size * 2; j++)
 
	double angle, cx = size / 2.;
	double sx[3], sy[3], sw[3];
	double fade[] = { 1, .35, .35 }; 
	struct timeval tv;
	struct tm *t;
 
	
	sw[sec] = size * .02;
	sw[min] = size * .03;
	sw[hur] = size * .05;
 
every_second:
	gettimeofday(&tv, 0);
	t = localtime(&tv.tv_sec);
 
	angle = t->tm_sec * PI / 30;
	sy[sec] = -cx * cos(angle);
	sx[sec] =  cx * sin(angle);
 
	angle = (t->tm_min + t->tm_sec / 60.) / 30 * PI;
	sy[min] = -cx * cos(angle) * .8;
	sx[min] =  cx * sin(angle) * .8;
 
	angle = (t->tm_hour + t->tm_min / 60.) / 6 * PI;
	sy[hur] = -cx * cos(angle) * .6;
	sx[hur] =  cx * sin(angle) * .6;
 
	printf("\033[s"); 
	for_i {
		printf("\033[%d;0H", i);  
		double y = i - cx;
		for_j {
			double x = (j - 2 * cx) / 2;
 
			int pix = 0;
			
			for (int k = hur; k >= sec; k--) {
				double d = dist(x, y, sx[k], sy[k]);
				if (d < sw[k] - .5)
					pix = 10 * fade[k];
				else if (d < sw[k] + .5)
					pix = (5 + (sw[k] - d) * 10) * fade[k];
			}
			putchar(shades[pix]);
		}
	}
	printf("\033[u"); 
 
	fflush(stdout);
	sleep(1); 
	goto every_second;
}
 
int main(int argc, char *argv[])
{
	int s;
	if (argc <= 1 || (s = atoi(argv[1])) <= 0) s = 20;
	draw(s);
	return 0;
}

C#: using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

public class Clock : Form
{
    static readonly float degrees06 = (float)Math.PI / 30;
    static readonly float degrees30 = degrees06 * 5;
    static readonly float degrees90 = degrees30 * 3;

    readonly int margin = 20;

    private Point p0;

    public Clock()
    {
        Size = new Size(500, 500);
        StartPosition = FormStartPosition.CenterScreen;
        Resize += (sender, args) => ResetSize();
        ResetSize();
        var timer = new Timer() { Interval = 1000, Enabled = true };
        timer.Tick += (sender, e) => Refresh();
        DoubleBuffered = true;
    }

    private void ResetSize()
    {
        p0 = new Point(ClientRectangle.Width / 2, ClientRectangle.Height / 2);
        Refresh();
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

        drawFace(e.Graphics);

        var time = DateTime.Now;
        int second = time.Second;
        int minute = time.Minute;
        int hour = time.Hour;

        float angle = degrees90 - (degrees06 * second);
        DrawHand(e.Graphics, Pens.Red, angle, 0.95);

        float minsecs = (minute + second / 60.0F);
        angle = degrees90 - (degrees06 * minsecs);
        DrawHand(e.Graphics, Pens.Black, angle, 0.9);

        float hourmins = (hour + minsecs / 60.0F);
        angle = degrees90 - (degrees30 * hourmins);
        DrawHand(e.Graphics, Pens.Black, angle, 0.6);
    }

    private void drawFace(Graphics g)
    {
        int radius = Math.Min(p0.X, p0.Y) - margin;
        g.FillEllipse(Brushes.White, p0.X - radius, p0.Y - radius, radius * 2, radius * 2);

        for (int h = 0; h < 12; h++)
            DrawHand(g, Pens.LightGray, h * degrees30, -0.05);

        for (int m = 0; m < 60; m++)
            DrawHand(g, Pens.LightGray, m * degrees06, -0.025);
    }

    private void DrawHand(Graphics g, Pen pen, float angle, double size)
    {
        int radius = Math.Min(p0.X, p0.Y) - margin;

        int x0 = p0.X + (size > 0 ? 0 : Convert.ToInt32(radius * (1 + size) * Math.Cos(angle)));
        int y0 = p0.Y + (size > 0 ? 0 : Convert.ToInt32(radius * (1 + size) * Math.Sin(-angle)));

        int x1 = p0.X + Convert.ToInt32(radius * (size > 0 ? size : 1) * Math.Cos(angle));
        int y1 = p0.Y + Convert.ToInt32(radius * (size > 0 ? size : 1) * Math.Sin(-angle));

        g.DrawLine(pen, x0, y0, x1, y1);
    }

    [STAThread]
    static void Main()
    {
        Application.Run(new Clock());
    }
}