View source for Langston's Ant, animated for POSIX

==Synopsis==

Performs a simulation of Langston's Ant as an animation for Linux, Un*x systems.

==Notes==

There are no borders, the map wraps edge to edge.  Define statements have a 20x20 grid, 1000 steps and a delay of 20ms.  The ANT always starts at, or near, the center.  The ant defaults being oriented towards north as an initial condition.

==Compilation==
<syntaxhighlight lang="bash">
gcc -o Ant Ant.c
</syntaxhighlight>
==Code==
<syntaxhighlight lang="C++" line='line'>
#include<stdio.h>
#include<stdlib.h>
#include <time.h>
#include <errno.h> 
#define X 20
#define Y 20
#define S 1000
#define D 20   

/* msleep(): Sleep for the requested number of milliseconds. */
int msleep(long msec)
{
	struct timespec ts;
	int res;

	if (msec < 0)
	{
		errno = EINVAL;
		return -1;
	}

	ts.tv_sec = msec / 1000;
	ts.tv_nsec = (msec % 1000) * 1000000;

	do
	{
		res = nanosleep(&ts, &ts);
	}
	while (res && errno == EINTR);
	return res;
}

void main(void)
{
	char world[X][Y];
	unsigned short x, y, c, d, h, s;
	//init
	x=X/2; y=Y/2; h=0;
	for(c=0;c<Y;c++)
	{
		for(d=0;d<X;d++)
		{
			world[d][c] = '.';
		}
	}

	//loop
	for(s=0;s<S;s++)
	{
		#ifdef D
		msleep(D);
		#endif
		printf("\e[1;1H\e[2J");
		//print current state
		printf("S=%d\n\n",s+1);
		printf("%c", '/');
		for(c=0;c<X;c++)
		{
			printf("%c", '-');
		}
		printf("%c\n", '\\');
		for(c=0;c<Y;c++)
		{
			printf("%c", '|');
			for(d=0;d<X;d++)
			{
				if(d==x && c==y)
					printf("A");
				else
					printf("%c",world[d][c]);
			}
			printf("%c\n", '|');
		}
		printf("%c", '\\');
		for(c=0;c<X;c++)
		{
			printf("%c", '-');
		}
		printf("/\n\n");
		//turn logic
		if(world[x][y]=='.')
		{
			h++; //CW
			h = h % 4;
			world[x][y]='*';
		}
		else
		{	
			h--; //CCW
			h= h % 4;
			world[x][y]='.';
		}
		//move forward
		if(h==0)
			{if(y==0) y=Y-1; else y--;}
		if(h==2)
			{if(y==Y-1) y=0; else y++;}
		if(h==1)
			{if(x==X-1) x=0; else x++;}
		if(h==3)
			{if(x==0) x=X-1; else x--;}
	}

	//terminate
	printf("\nEOS \n");
	return;
}
</syntaxhighlight>