Please help me tweak the Homing pigeon exercise

balqan · February 16th, 2012, 10:35 AM

I'm going trough the book of Matt Doyle, Beginning PHP 5.3, so far so good, but for the sake of fun, I would like to take the Homing pigeon exercises a bit further and I'm getting stuck. The "pigeon" (%) gets assigned a random x and y and it goes "home" (+).

I tweaked the code to have two pigeons and was working fine, but now I try to make it with an eagle, called "sas" (W) that should ignore the "home" and focus on hunting the pigeon. Whoever gets first, the pigeon home, or the eagle to catch the pigeon, the game should stop.

I can't get the eagle to hunt the pigeon, I don't know what I'm doing wrong... It's behaving the same way as the pigeon...

I wonder if anyone could point me to the right direction. Thanks.

PHP Code:


			
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

<title>Homing pigeon simulator</title>

<style type="text/css">

div.map {

        float:left;

        text-align:center;

        border:1px solid #666;

        background-color:#fcfcfc;

        margin:5px;

        padding:1em;

}

span.home, span.bird{

        font-weight:bold;

}

span.empty{

        color:#666;

}

</style>

</head>



<body>

<?php



$mapSize = 10;



//position the home and the pigeon



do {

        $homeX = rand ( 0, $mapSize-1);

        $homeY = rand ( 0, $mapSize-1);

        $pigeonX = rand (0, $mapSize-1);

        $pigeonY = rand (0, $mapSize-1);

        $sasX = rand (0, $mapSize-1);

        $sasY = rand (0, $mapSize-1);

} while ( (abs($homeX - $pigeonX ) < $mapSize/2) && (abs( $homeY - $pigeonY ) < $mapSize/2) && (abs($pigeonX - $sasX ) < $mapSize/2) && (abs( $pigeonY - $sasY ) < $mapSize/2));



//move the pigeon closer to target

do {

        if ( $pigeonX < $homeX)

                $pigeonX++;

        elseif ( $pigeonX > $homeX)

                $pigeonX--;

        if ( $pigeonY < $homeY )

                $pigeonY++;

        elseif ($pigeonY > $homeY)

                $pigeonY--;

        if ( $sasX < $pigeonX)

                $sasX++;

        elseif ( $sasX > $pigeonX)

                $sasX--;

        if ( $sasY < $pigeonY )

                $sasY++;

        elseif ($sasY > $pigeonY)

                $sasY--;

        

        //display the current map

        

        echo '<div class="map" style="width:'. $mapSize .'em;"><pre>';

        

        for ( $y = 0; $y < $mapSize; $y++) {

                for ( $x = 0; $x < $mapSize; $x++) {

                        if ($x==$homeX && $y == $homeY) {

                                echo '<span class="home">+</span>'; //Home      

                        } elseif ( $x == $pigeonX && $y == $pigeonY) {

                                echo '<span class="bird">%</span>'; // Pigeon   

                        } elseif ($x == $sasX && $y == $sasY) {

                                echo '<span class="bird">W</span>';

                        }       else {

                                echo '<span class="empty">.</span>';

                        }

                        

                        echo ( $x != $mapSize-1) ? " " : " ";

                }

                echo "\n";

        }

        echo "</pre></div>\n";

} while ($pigeonX != $homeX || $pigeonY != $homeY || $pigeonX != $sasX || $pigeonY != $sasY);

?>



</body>

</html>

balqan · February 25th, 2012, 07:06 PM

Hi all,

A dear friend has helped me out with this puzzle and showed me how to solve it. On page 44, you get more info about the difference between == and ===

To make it easier to understand the eagle is E and the pigeon is P:

Code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
<title>Homing pigeon simulator</title> 
<style type="text/css"> 
div.map { 
        float:left; 
        text-align:center; 
        border:1px solid #666; 
        background-color:#fcfcfc; 
        margin:5px; 
        padding:1em; 
} 
span.home, span.bird{ 
        font-weight:bold; 
} 
span.empty{ 
        color:#666; 
} 
</style> 
</head> 

<body> 
<?php 

$mapSize = 10; 

//position the home and the pigeon 

do { 
        $homeX = rand ( 0, $mapSize-1); 
        $homeY = rand ( 0, $mapSize-1); 
        $pigeonX = rand (0, $mapSize-1); 
        $pigeonY = rand (0, $mapSize-1); 
        $sasX = rand (0, $mapSize-1); 
        $sasY = rand (0, $mapSize-1); 
} while ( 
	(abs($homeX - $pigeonX ) < $mapSize/2) 
	&& (abs( $homeY - $pigeonY ) < $mapSize/2) 
	&& (abs($pigeonX - $sasX ) < $mapSize/2) 
	&& (abs( $pigeonY - $sasY ) < $mapSize/2)
); 

//move the pigeon closer to target 
do { 
        if ( $pigeonX < $homeX)
            $pigeonX++; 
        elseif ( $pigeonX > $homeX) 
            $pigeonX--; 
        if ( $pigeonY < $homeY ) 
            $pigeonY++; 
        elseif ($pigeonY > $homeY) 
            $pigeonY--; 
        if ( $sasX < $pigeonX) 
            $sasX++; 
        elseif ( $sasX > $pigeonX) 
            $sasX--; 
        if ( $sasY < $pigeonY ) 
            $sasY++; 
        elseif ($sasY > $pigeonY) 
            $sasY--; 
         
        //display the current map 
         
        echo '<div class="map" style="width:'. $mapSize .'em;"><pre>'; 
         
        for ( $y = 0; $y < $mapSize ; $y++) { 
                for ( $x = 0; $x < $mapSize; $x++ ) { 
                        if ( $x === $homeX && $y === $homeY ) { 
                        	// Home
                        	echo '<span class="home">+</span>';      
                        } elseif ( $x === $sasX && $y === $sasY ) { 
                        	// Eagle 
                            echo '<span class="bird">E</span>'; 
                        } elseif ( $x === $pigeonX && $y === $pigeonY ) {
	                        // Pigeon 
                            echo '<span class="bird">P</span>'; 
                        } else { 
                            echo '<span class="empty">.</span>'; 
                        } 
                         
                        echo  " "; 
                } 
                echo "\n"; 
        } 
        echo "</pre></div>\n"; 
} while (
	!($pigeonX === $homeX && $pigeonY === $homeY) 
	&& !($pigeonX === $sasX && $pigeonY === $sasY)
);

?> 

</body> 
</html>