php classes, arrays

towlie · 05-25-2005, 02:21 PM

Hey everyone, I have no idea what I'm doing wrong
and I feel really stupid, have looked at php's manual
but don't know what to do.

In the code below, if you uncomment the line in the
function setRow(), it gets stuck in an infinite loop. As
it turns out, my assignment to what is supposed to be
one of the member variables (an array, $data), is actually
assigning to one of the other member variables ($numRows).

WTF is that?!!!

I'm a c(++) background, so this syntax is kinda weird to
me (having to put $this before everything, so annoying!).

The program's supposed to check if the (2-d) array is big enough,
and if not add enough rows (however many user wants). Can
someone please correct my php? Thanks.

PHP Code:



<?php 
// classes for making and printing tables 
 
class cell 
{ 
    public $rspan, $cspan, $data; 
 
    public function __construct() 
    { 
        $argc= func_num_args(); 
        $args= func_get_args(); 
 
        $d= ($argc > 0)? $args[0] : null; 
        $r= ($argc > 2)? $args[1] : null; 
        $c= ($argc > 2)? $args[2] : null; 
 
        $data= $d; 
        $rspan= ($r > -1)? $r : 0; 
        $cspan= ($c > -1)? $c : 0; 
    } 
} 
 
 
class table 
{ 
    private $numRows, $numCols, $data; 
    public $htmlAtts, $htmlRowClass; 
 
 
    public function __construct() 
    { 
        $argc= func_num_args(); 
        $args= func_get_args(); 
 
        $this->$data= array(); 
        $this->$htmlAtts= array(); 
        $this->$htmlRowClass= array(); 
 
        if($argc < 2) {$r= $c= 0;} 
        else 
        { 
            $r= $argv[0]; 
            $c= $argv[1]; 
        } 
 
        $this->$numRows= ($r > -1)? $r : 0; 
        $this->$numCols= ($c > -1)? $c : 0; 
    } 
 
 
    // set a row's cells to the given array 
    public function setRow($r, $arr) 
    { 
        print 'r:        '. print_r($r, TRUE) ."\n"; 
        print 'arr:      '. print_r($arr, TRUE) ."\n"; 
        print 'num rows: '. print_r($this->$numRows, TRUE) ."\n\n\n"; 
 
        if($r < 0) return FALSE; 
        if($r >= $this->$numRows)  // add enough space 
        { 
            for($i= count($this->$data); $i <= $r; $i++) 
                $this->$data[$i]= array(); 
            $this->$numRows= $r + 1; 
        } 
        for($i= 0; $i < count($arr); $i++) 
            //$this->$data[$r][$i]= new cell($arr[$i]);    // PROBLEM HERE 
        return TRUE; 
    } 
 
 
    public function htmlStr() 
    { 
        print "num rows: ". print_r($this->$numRows, TRUE) ."\n\nnum cols: ". $this->$numCols ."\n\n"; 
        $ret= '<table'; 
        foreach($this->$htmlAtts as $k => $v) {$ret .= " $k=\"$v\"";} 
        $ret .= '>'; 
 
        for($r= 0; $r < $this->$numRows; $r++) 
        { 
            //print "fjksjl"; 
            $rowClass= ''; 
            $x= count($this->$htmlRowClass); 
            if($x > 0) $rowClass= ' class="'. $this->$htmlRowClass[$r % $x] .'"'; 
 
            $ret .= '<tr'. $rowClass .'>'; 
 
            for($c= 0; $c < $this->$numCols; $c++) 
            { 
            //print "rioweuprw"; 
                $temp= $this->$data[$r][$c]; 
 
                if($temp !== null  &&  $temp->$rspan > 0  &&  $temp->$cspan > 0) 
                    $ret .= '<td>'. htmlentities($temp->$data) .'</td>'; 
            } 
 
            $ret .= '</tr>'; 
        } 
 
        return $ret . '</table>'; 
    } 
} 
?> 
 
<html><body> 
 
 
<?php 
$t= new table(); 
$t->setRow(0, array(1, 2, 3)); 
$t->setRow(1, array(4, 5, 6)); 
$t->setRow(2, array(7, 8, 9)); 
print $t->htmlStr(); 
 
 
?> 
 
 
 
 
</body></html>

jiml8 · 05-25-2005, 11:22 PM

count(arr$) is a function that is being re-evaluated each time through the loop. You are adding a cell each time through the loop, so count(arr$) increases each time through. Hence you never reach the end.
Replace the function with a constant and then I'll bet it works.

towlie · 05-26-2005, 08:54 AM

jiml8:

Thanks, but $arr isn't being changed there, what's being
changed is $this->$data[$r][0] ..... $this->$data[$r][n-1], where
n is the length of $arr. But $arr is still constant in that function.

For example, this does the same thing:

PHP Code:



for($i= 0, $j= count($arr); $i < $j; $i++) 
    $this->$data[$r][$i]= new cell($arr[$i]);    // PROBLEM HERE

That was the spot you're talking about right?

Anyway, does this have something to do with the variable being
allocated and then overwritten unintentionally (has anyone seen
that before in php) or am I just messing it up somewhere?

thanx everyone.

towlie · 05-26-2005, 01:58 PM

Wrote a little more but haven't figured it out yet.

It no longer gets in an infinite loop, but for some reason
$this->$data never gets made into an array, so
$this->$data[n] can never get made into arrays themselves.

Probably some stupid syntax mistake I have, anyone see
what it is? Thanx

PHP Code:



<?php 
// classes for making and printing tables 
 
class cell 
{ 
    public $rspan, $cspan, $data; 
 
    public function __construct() 
    { 
        $argc= func_num_args(); 
        $args= func_get_args(); 
 
        $d= ($argc > 0)? $args[0] : null; 
        $r= ($argc > 2)? $args[1] : null; 
        $c= ($argc > 2)? $args[2] : null; 
 
        $data= $d; 
        $rspan= ($r > -1)? $r : 0; 
        $cspan= ($c > -1)? $c : 0; 
    } 
} 
 
 
class table 
{ 
    private $numRows, $numCols, $data; 
    public $htmlAtts, $htmlRowClass; 
 
 
    public function __construct() 
    { 
        $argc= func_num_args(); 
        $args= func_get_args(); 
 
        $this->$data= array(); 
        $this->$htmlAtts= array(); 
        $this->$htmlRowClass= array(); 
 
        if($argc < 2) {$r= $c= 0;} 
        else 
        { 
            $r= $argv[0]; 
            $c= $argv[1]; 
        } 
 
        $this->$numRows= ($r > -1)? $r : 0; 
        $this->$numCols= ($c > -1)? $c : 0; 
 
        print "finished __construct()\n\n\n"; 
        print_r($this); 
    } 
 
 
    // set a row's cells to the given array 
    public function setRow($r, $arr) 
    { 
        print 'r:        '. print_r($r, TRUE) ."\n"; 
        print 'arr:      '. print_r($arr, TRUE) ."\n"; 
        print 'num rows: '. print_r($this->$numRows, TRUE) ."\n\n\n"; 
 
        print "data: ". print_r($this->$data, TRUE) . "\n\n\n\n\n"; 
 
        if($r < 0) return FALSE; 
        if($r >= $this->$numRows)  // add enough space 
        { 
            for($i= count($this->$data); $i <= $r; $i++) 
                $this->$data[$i]= array(); 
            $this->$numRows= $r + 1; 
        } 
 
        for($i= 0, $j= count($arr); $i < $j; $i++) 
            array_push($this->$data[$r], new cell($arr[$i]));    // PROBLEM HERE 
        return TRUE; 
    } 
 
 
    public function htmlStr() 
    { 
        print "num rows: ". print_r($this->$numRows, TRUE) ."\n\nnum cols: ". $this->$numCols ."\n\n"; 
        $ret= '<table'; 
        foreach($this->$htmlAtts as $k => $v) {$ret .= " $k=\"$v\"";} 
        $ret .= '>'; 
 
        for($r= 0; $r < $this->$numRows; $r++) 
        { 
            //print "fjksjl"; 
            $rowClass= ''; 
            $x= count($this->$htmlRowClass); 
            if($x > 0) $rowClass= ' class="'. $this->$htmlRowClass[$r % $x] .'"'; 
 
            $ret .= '<tr'. $rowClass .'>'; 
 
            for($c= 0; $c < $this->$numCols; $c++) 
            { 
            //print "rioweuprw"; 
                $temp= $this->$data[$r][$c]; 
 
                if($temp !== null  &&  $temp->$rspan > 0  &&  $temp->$cspan > 0) 
                    $ret .= '<td>'. htmlentities($temp->$data) .'</td>'; 
            } 
 
            $ret .= '</tr>'; 
        } 
 
        return $ret . '</table>'; 
    } 
} 
?> 
 
<html><body> 
 
 
<?php 
$t= new table(); 
$t->setRow(0, array(1, 2, 3)); 
$t->setRow(1, array(4, 5, 6)); 
$t->setRow(2, array(7, 8, 9)); 
print $t->htmlStr(); 
?> 
 
</body></html>

towlie · 05-27-2005, 11:44 AM

Okay, I made an example script just to see if I'm doing my
php syntax right, but I'm not, and php.net and tutorials
aren't really helping.

If anyone can explain what I'm doing wrong here, I'd really
appreciate it. And if anyone can help me with the other, bigger
program (one I'm really working on) that would be great too.

Also anyone know why print_r doesn't print the class members
when given a class? My own tostr() func says the members
are set to a number (wrong number though), but print_r
lists that number in private, what's that about?

Here's my version:

Code:

PHP 5.0.4 (cli) (built: Mar 31 2005 02:45:48)
Copyright (c) 1997-2004 The PHP Group
Zend Engine v2.0.4-dev, Copyright (c) 1998-2004 Zend Technologies

Here's the code I can't get working:

PHP Code:



<?php 
 
// example class 
class point 
{ 
    public $x, $y; 
 
 
    public function __construct($X= 0, $Y= 0) 
    { 
        $this->$x= $X;  $this->$y= $Y; 
    } 
 
 
    public function add($a)  // add a point or scalar 
    { 
        $ret= new point(); 
 
        if($a instanceof point) 
        { 
            $ret->$x= $this->$x + $a->$x; 
            $ret->$y= $this->$y + $a->$y; 
        } 
 
        else if(is_double($a)  ||  is_int($a)) 
        { 
            $ret->$x= $this->$x + $a; 
            $ret->$y= $this->$y + $a; 
        } 
 
        return $ret; 
    } 
 
 
    public function mul($a)  // multiply a point or scalar 
    { 
        $ret= new point(); 
 
        if($a instanceof point) 
        { 
            $ret->$x= $this->$x * $a->$x; 
            $ret->$y= $this->$y * $a->$y; 
        } 
 
        else if(is_double($a)  ||  is_int($a)) 
        { 
            $ret->$x= $this->$x * $a; 
            $ret->$y= $this->$y * $a; 
        } 
 
        return $ret; 
    } 
 
 
    public function tostr()  // to readable string 
    { 
        return '('. $this->$x .', '. $this->$y .')'; 
    } 
} 
 
 
 
$z1= new point; 
$z2= new point(); 
$a= new point(3, 4); 
$b= new point(7, 8); 
 
 
 
$res= array( 
    'z1'      => $z1, 
    'z2'      => $z2, 
    'a + b'   => $a->add($b), 
    'b + a'   => $b->add($a), 
    'a * b'   => $a->mul($b), 
    'b * a'   => $b->mul($a), 
    'a + 4.8' => $a->add(4.8), 
    'b - 4.8' => $b->add(-4.8)); 
 
$res['mid']= $res['a + b']->mul(0.5); 
 
 
 
// cross our fingers and print the results 
foreach($res as $k => $v) 
    print "$k: ". $v->tostr() ."\n". print_r($v, TRUE) ."\n\n"; 
 
 
?>

LLS · 05-28-2005, 10:43 AM

Have you looked through this?

http://www.phpfreaks.com/phpmanual/page/ref.classobj.html

I am interested to see what your solution is.

towlie · 05-28-2005, 11:21 AM

LLS, thanks for the link, I will check it out. If I figure
this out I'll post the solution when finished.

towlie · 05-29-2005, 03:42 PM

yeah, like i thought, dumb mistake

you have to use this:

Code:

$myClass->myVar;
$myClass->myFunc();

not this:

Code:

$myClass->$myVar;
$myClass->myFunc();

LLS · 05-29-2005, 04:34 PM

If you have the chance, could you point at a section of code in your second example, or first that this revelation applies to? Thanks much for sharing your solution.

towlie · 05-29-2005, 06:07 PM

So from the 2nd example I had:

Code:

// this is WRONG
if($a instanceof point)
{
    $ret->$x= $this->$x + $a->$x;
    $ret->$y= $this->$y + $a->$y;
}


// the above should be changed to this
if($a instanceof point)
{
    $ret->x= $this->x + $a->x;
    $ret->y= $this->y + $a->y;
}

towlie · 06-07-2005, 11:10 AM

Here is the result of my work if anyone is interested:
http://galaxy.cs.lamar.edu/~ja137401...057/index.html