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;
}

Java: import java.awt.*;
import java.awt.event.*;
import static java.lang.Math.*;
import java.time.LocalTime;
import javax.swing.*;

class Clock extends JPanel {

    final float degrees06 = (float) (PI / 30);
    final float degrees30 = degrees06 * 5;
    final float degrees90 = degrees30 * 3;

    final int size = 590;
    final int spacing = 40;
    final int diameter = size - 2 * spacing;
    final int cx = diameter / 2 + spacing;
    final int cy = diameter / 2 + spacing;

    public Clock() {
        setPreferredSize(new Dimension(size, size));
        setBackground(Color.white);

        new Timer(1000, (ActionEvent e) -> {
            repaint();
        }).start();
    }

    @Override
    public void paintComponent(Graphics gg) {
        super.paintComponent(gg);
        Graphics2D g = (Graphics2D) gg;
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        drawFace(g);

        final LocalTime time  = LocalTime.now();
        int hour = time.getHour();
        int minute = time.getMinute();
        int second = time.getSecond();

        float angle = degrees90 - (degrees06 * second);
        drawHand(g, angle, diameter / 2 - 30, Color.red);

        float minsecs = (minute + second / 60.0F);
        angle = degrees90 - (degrees06 * minsecs);
        drawHand(g, angle, diameter / 3 + 10, Color.black);

        float hourmins = (hour + minsecs / 60.0F);
        angle = degrees90 - (degrees30 * hourmins);
        drawHand(g, angle, diameter / 4 + 10, Color.black);
    }

    private void drawFace(Graphics2D g) {
        g.setStroke(new BasicStroke(2));
        g.setColor(Color.white);
        g.fillOval(spacing, spacing, diameter, diameter);
        g.setColor(Color.black);
        g.drawOval(spacing, spacing, diameter, diameter);
    }

    private void drawHand(Graphics2D g, float angle, int radius, Color color) {
        int x = cx + (int) (radius * cos(angle));
        int y = cy - (int) (radius * sin(angle));
        g.setColor(color);
        g.drawLine(cx, cy, x, y);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setTitle("Clock");
            f.setResizable(false);
            f.add(new Clock(), BorderLayout.CENTER);
            f.pack();
            f.setLocationRelativeTo(null);
            f.setVisible(true);
        });
    }
}