Inspired by the show 24, I decided to try and re-create the famous clock in a linux terminal. To compile the app, you'll need to have ncurses installed, to do that use the following command in a debian environment. sudo apt-get install ncurses-dev Once that is installed, compilation is pretty straight-forward, paste the following into your termi…

24.c

#include <stdio.h>
#include <curses.h>
#include <time.h>

#define HORIZONTAL_BAR_LEN			3
#define VERTICAL_BAR_LEN 			2

#define DIGIT_WIDTH				((HORIZONTAL_BAR_LEN * 2) + 5)
#define DIGIT_HEIGHT				((VERTICAL_BAR_LEN * 2) + 3)

void drawHorizontalBar				(int x, int y, int len);
void drawVerticalBar				(int x, int y, int len);

void drawTopLeft				(int x, int y);
void drawTopRight				(int x, int y);
void drawRightTop				(int x, int y);
void drawRightBottom				(int x, int y);
void drawMiddleLeft				(int x, int y);
void drawMiddleRight				(int x, int y);
void drawLeftTop				(int x, int y);
void drawLeftBottom				(int x, int y);
void drawBottomLeft				(int x, int y);
void drawBottomRight				(int x, int y);

void draw0					(int x, int y);
void draw1					(int x, int y);
void draw2					(int x, int y);
void draw3					(int x, int y);
void draw4					(int x, int y);
void draw5					(int x, int y);
void draw6					(int x, int y);
void draw7					(int x, int y);
void draw8					(int x, int y);
void draw9					(int x, int y);

void drawDigit					(unsigned char digit, int x, int y);
void drawColon					(int x, int y);

int main()
{
	initscr();
	noecho();
	curs_set(0);

	// get the dimensions of the screen
	int maxX, maxY;
	getmaxyx(stdscr, maxY, maxX);

	// make sure there's enough room for the clock
	if (12 + 6 * DIGIT_WIDTH > maxX + 1 || DIGIT_HEIGHT > maxY + 1)
	{
		move(0, 0);
		printw("This terminal is too small to display the clock, make it larger and try again.");

		refresh();
		getch();	
		endwin();
		return 0;
	}

	// calculate the coordinates to put the digits on the screen
	int yPos = (maxY / 2) - (2 * VERTICAL_BAR_LEN);

	// stores the time digits, so 12:48:26 would be { 1, 2, 4, 8, 2, 6 }
	unsigned char timeNums[6] = { 0 };
	unsigned char prevSec = 0xFF;

	// forever, the user can stop it with an interrupt
	for (;;)
	{
		// get the current system time
		time_t rawCurTime = time(NULL);
		struct tm *curTime = localtime(&rawCurTime);

		// calculate all of the digits that we want to display on the screen
		timeNums[0] = curTime->tm_hour / 10;
		timeNums[1] = curTime->tm_hour % 10;
		timeNums[2] = curTime->tm_min / 10;
		timeNums[3] = curTime->tm_min % 10;
		timeNums[4] = curTime->tm_sec / 10;
		timeNums[5] = curTime->tm_sec % 10;

		// if the time didn't change, then don't redraw
		if (prevSec == timeNums[5])
			continue;
		
		// clear all of the current numbers from the screen
		clear();

		// draw all of the time digits onto the screen
		drawDigit(timeNums[0], 4, yPos);
		drawDigit(timeNums[1], 4 + DIGIT_WIDTH, yPos);

		drawColon(4 + 2 * DIGIT_WIDTH + 1, yPos);

		drawDigit(timeNums[2], 4 + 2 * DIGIT_WIDTH + 4, yPos);
		drawDigit(timeNums[3], 4 + 3 * DIGIT_WIDTH + 4, yPos);

		drawColon(4 + 4 * DIGIT_WIDTH + 5, yPos);

		drawDigit(timeNums[4], 4 + 4 * DIGIT_WIDTH + 8, yPos);
		drawDigit(timeNums[5], 4 + 5 * DIGIT_WIDTH + 8, yPos);

		// update the prev time so that it won't redraw every iteration
		prevSec = timeNums[5];

		refresh();
	}

	refresh();
	getch();	

	endwin();
	return 0;
}

void drawVerticalBar(int x, int y, int len)
{
	for (int i = 0; i < len; i++)
	{
		move(y++, x);
		addch(' '|A_REVERSE);
	}
}

void drawHorizontalBar(int x, int y, int len)
{
	move(y, x);
	for (int i = 0; i < len; i++)
		addch(' '|A_REVERSE);
}

inline void drawTopLeft(int x, int y)
{
	drawHorizontalBar(x + 1, y, HORIZONTAL_BAR_LEN);
}

inline void drawTopRight(int x, int y)
{
	drawHorizontalBar(x + HORIZONTAL_BAR_LEN + 2, y, HORIZONTAL_BAR_LEN);
}

inline void drawRightTop(int x, int y)
{
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y + 1, VERTICAL_BAR_LEN);
}

inline void drawRightBottom(int x, int y)
{
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y + VERTICAL_BAR_LEN + 2, VERTICAL_BAR_LEN);
}

inline void drawMiddleLeft(int x, int y)
{
	drawHorizontalBar(x + 1, y + VERTICAL_BAR_LEN + 1, HORIZONTAL_BAR_LEN);
}

inline void drawMiddleRight(int x, int y)
{
	drawHorizontalBar(x + HORIZONTAL_BAR_LEN + 2, y + VERTICAL_BAR_LEN + 1, HORIZONTAL_BAR_LEN);
}

inline void drawLeftTop(int x, int y)
{
	drawVerticalBar(x, y + 1, VERTICAL_BAR_LEN);
}

inline void drawLeftBottom(int x, int y)
{
	drawVerticalBar(x, y + VERTICAL_BAR_LEN + 2, VERTICAL_BAR_LEN);
}

inline void drawBottomLeft(int x, int y)
{
	drawHorizontalBar(x + 1, y + 2 * VERTICAL_BAR_LEN + 2, HORIZONTAL_BAR_LEN);
}

inline void drawBottomRight(int x, int y)
{
	drawHorizontalBar(x + HORIZONTAL_BAR_LEN + 2, y + 2 * VERTICAL_BAR_LEN + 2, HORIZONTAL_BAR_LEN);
}

void draw0(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	drawRightBottom(x, y);

	drawLeftTop(x, y);
	drawLeftBottom(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw1(int x, int y)
{
	// so it extends the full length
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y, 1);
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y + 2 * VERTICAL_BAR_LEN + 2, 1);

	drawRightTop(x, y);
	drawRightBottom(x, y);
}

void draw2(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftBottom(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw3(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw4(int x, int y)
{
	// so it extends the full length
	drawVerticalBar(x, y, 1);
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y, 1);
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y + 2 * VERTICAL_BAR_LEN + 2, 1);

	drawRightTop(x, y);
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftTop(x, y);
}

void draw5(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftTop(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw6(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftTop(x, y);
	drawLeftBottom(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw7(int x, int y)
{
	// so it extends the full length
	drawVerticalBar(x + 2 * HORIZONTAL_BAR_LEN + 2, y + 2 * VERTICAL_BAR_LEN + 2, 1);

	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	drawRightBottom(x, y);
}

void draw8(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftTop(x, y);
	drawLeftBottom(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void draw9(int x, int y)
{
	drawTopLeft(x, y);
	drawTopRight(x, y);
	
	drawRightTop(x, y);
	drawRightBottom(x, y);
	
	drawMiddleLeft(x, y);
	drawMiddleRight(x, y);

	drawLeftTop(x, y);

	drawBottomLeft(x, y);
	drawBottomRight(x, y);
}

void drawDigit(unsigned char digit, int x, int y)
{
	switch (digit)
	{
		case 0:
			draw0(x, y);
			break;
		case 1:
			draw1(x, y);
			break;
		case 2:
			draw2(x, y);
			break;
		case 3:
			draw3(x, y);
			break;
		case 4:
			draw4(x, y);
			break;
		case 5:
			draw5(x, y);
			break;
		case 6:
			draw6(x, y);
			break;
		case 7:
			draw7(x, y);
			break;
		case 8:
			draw8(x, y);
			break;
		case 9:
			draw9(x, y);
			break;
	}
}

void drawColon(int x, int y)
{
	int third = (2 * VERTICAL_BAR_LEN + 3) / 3;

	drawVerticalBar(x, y + third, 1);
	drawVerticalBar(x, y + 2 * third, 1);
}