//-------------------------------------------------------------------
//	iseven.cpp
//
//	This is a high-level language 'prototype' (written in C++)
//	for a program you are asked to write in assembly-language.
//	In case a number is entered as a command-line argument, it
//	determines whether or not that number was an even integer.  
//
//	   compile-and-link using:  $ g++ iseven.cpp -o iseven
//	   and then execute using:  $ ./iseven <number>
//
//	NOTE: The purpose of a 'prototype' is to help you identify
//	all the program-variables and algorithm-steps your program
//	will need.  Of course, your assembly language program will
//	not necessarily find its command-line argument in the same
//	way that C++ does, nor will it be allowed to call standard
//	functions in the C/C++ runtime-libraries, but it will need 
//	to use its own ways of accomplishing those same effects.   
//
//	programmer: ALLAN CRUSE
//	written on: 25 FEB 2007
//-------------------------------------------------------------------

#include <stdlib.h>	// for exit(), atoi() 
#include <string.h>	// for strlen()
#include <unistd.h>	// for write() 

int main( int argc, char **argv )
{
	// exit in case the command-line argument is missing
	if ( argc == 1 ) exit(1);
	
	// otherwise convert the argument-string to an integer
	int	arg = atoi( argv[1] );

	// then report on whether the number is even or not
	int	remainder = arg % 2;
	int	arglength = strlen( argv[1] );
	write( STDOUT_FILENO, argv[1], arglength );
	if ( remainder == 0 )
		{ 
		char	message0[] = " is an even number \n";
		int	msg0len = strlen( message0 );
		write( STDOUT_FILENO, message0, msg0len );
		}
	else	{ 
		char	message1[] = " is not an even number \n";
		int	msg1len = strlen( message1 );
		write( STDOUT_FILENO, message1, msg1len );
		}
}