/*++
/* NAME
/*	hideaddr 1
/* SUMMARY
/*	Encodes an email address using HTML numeric character references.
/* SYNOPSIS
/*	hideraddr <email_address>
/* DESCRIPTION
/*	In order to prevent web-based email address harvesters from
/*	detecting email addresses in web pages, hideaddr converts
/*	an address into the HTML numeric codes for each character.
/*	It prints the numeric character references on standard output
/*	so the code string can be redirected or cut and pasted into
/*	an HTML file.
/*
/*	You need a C compiler to build hideaddr. Type
/*
/*		$ cc -o hideaddr hideaddr.c
/*
/*	Of course, encoding your email address in this way is not
/*	a guarantee that address harvesters won't find it. Any of the
/*	tricks people use (e.g. "kyle at example dot com") to hide
/*	email addresses on web pages are susceptible to smart
/*	harvesters, but this has the advantage of looking normal to
/*	users through their browsers and allowing you to create
/*	hyperlinks for your email addresses.
/*
/*	After you've built the utility, execute it as follows:
/*
/*		$ ./hideaddr kdent@example.com
/*
/*	which will produce a lengthy string like so:
/*
/*	&#107;&#100;&#101;&#110;&#116;&#64;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#99;&#111;&#109;
/*
/*	Cut and paste this long string of characters into your
/*	web page. A mailto link should look something like this:
/*
/*	<a href="mailto:&#107;&#100;&#101;&#110;&#116;&#64;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#99;&#111;&#109;">
/*	&#107;&#100;&#101;&#110;&#116;&#64;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#99;&#111;&#109;
/*	</a>
/*
/*	If this displays unwanted spaces around the address in your
/*	web page, put it all on one line.
/*
/* AUTHOR
/*	Kyle Dent
/*	January 28, 2003
/*--*/

#include <stdio.h>

int
main(int argc, char **argv)
{
	int n;

	if ( argc != 2 ) {
		fprintf(stderr, "Usage: hideaddr <email_address>\n");
		exit(1);
	}

	for ( n = 0; n < strlen(argv[1]); n++ ) {
		printf("&#%d;", argv[1][n]);
	}
	puts("");
}