displaying even/odd items of an array

[superkingkong]

hi guys,

 

for eg, i have a listing of files in a directory, assigned to an array

 

eg,

 

abc.txt

def.txt

ghi.txt

jkl.txt

mno.txt

pqr.txt

stu.txt

vwx.txt

yz.txt

 

how can i display the even count or odd count of them?

 

eg,

abc.txt

ghi.txt

mno.txt

stu.txt

yz.txt

 

or

 

def.txt

jkl.txt

pqr.txt

vwx.txt

 

your help is very much appreciated, thanks

[JasonLewis]

Use a for() loop and set the start at either 0 or 1 then go up in increments of 2.

 

$type = 1; //Odd;
for($i = $type; $i < count($your_array); $i += 2){
//do stuff here
}

[superkingkong]

Use a for() loop and set the start at either 0 or 1 then go up in increments of 2.

 

$type = 1; //Odd;
for($i = $type; $i < count($your_array); $i += 2){
//do stuff here
}

 

Hi,

 

thank you so much :)

[DarkWater]

@ProjectFear: Using count() on every iteration is SLOW.  This is probably faster:

 

<?php
foreach (glob('*') as $num => $name) {
    if ($num & 1) { continue; }
    echo "$name\n";
}
?>

 

To change it to even numbers, add a ! in front of $num in the if condition.

[JasonLewis]

Really? I use count() a fair bit in loops actually... I suppose I should be counting and storing it in a variable then using that variable instead.

 

So instead of:

 

for($i = 0; $i < count($array); $i++){

 

It'd be:

 

$count = count($array);
for($i = 0; $i < $count; $i++){

 

That would be faster, yes?

[superkingkong]

ooh...

 

here is my code.... wonder whether if you can help me to "streamline" it

 

<?php
$viewExt = '.jpg|.jpeg|.tif|.tiff|.gif|.png|.pdf|.txt';   // only filenames with these extensions will be displayed
$dirHandle = opendir('../upload');
$fcount = 0;
while ($file = readdir($dirHandle)) {
	if ($file != '.' && $file != '..' && eregi("($viewExt)$",$file) && !eregi("^index.",$file)) {
		$stack[] = $file;   // append filename to an array
		$fcount  ++;
	}
}

closedir($dirHandle);
sort($stack);

echo "<table border=1><tr><td colspan='2' align='center'><b>Your Uploaded Files</b></td></tr><tr><td>";

$type = 0; //Even;
for($i = $type; $i < count($stack); $i += 2){
	echo "<br><font color='#ff0000'><b>&#149;</b></font> " . $stack[$i];
}

echo "</td><td>";

$type = 1; //Odd;
for($i = $type; $i < count($stack); $i += 2){
	echo "<br><font color='#ff0000'><b>&#149;</b></font> " . $stack[$i];
}

echo "</tr><tr><td colspan='2' align='center'><b>Total Uploaded Files:" . $fcount . "</b></td></tr></table>";
?>

 

thank you very much :)

[xtopolis]

@ ProjectFear

Yes, a bottleneck in code is performing count x number of times on an array/loop that stays the same length.  Doing the same thing once >faster than> doing the same thing 50 times for the same result.  Just as your example is how it should be done.

 

@superkingkong

Not much smaller.

<?php
  $dir = './upload/';
  $files = glob("$dir{*.jpg,*.jpeg,*.tif,*.tiff,*.gif,*.png,*.pdf,*.txt,*.JPG,*.JPEG,*.TIF,*.TIFF,*.GIF,*.PNG,*.PDF,*.TXT}", GLOB_BRACE);
  sort($files);

  $i = 0;
  $left='';$right='';
  foreach($files as $file){
    $file = str_replace($dir, '', $file);
    if(($i % 2) == 0 || $i == 0){
      $left .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
    }else{
      $right .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
    }
    $i++;
  }
  echo "<table border=1><tr><td colspan='2' align='center'><b>Your Uploaded Files</b></td></tr><tr><td>";
    echo $left;
  echo "</td><td>";
    echo $right;
  echo "</td></tr><tr><td colspan='2' align='center'><b>Total Uploaded Files:" . count($files) . "</b></td></tr></table>";
?>

[Mark Baker]

<?php
if(($i % 2) == 0 || $i == 0){
  $left .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
}else{
  $right .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
}
$i++;

=>

<?php
if(($i++ % 2) == 0){
  $left .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
}else{
  $right .= "<br><font color='#ff0000'><b>&#149;</b></font>$file";
}

 

[Mark Baker]

Fractionally faster still if you pre-increment, and compare with 1 rather than 0

if((++$i % 2) == 1){
  $left .= "<br><font color='#ff0000'><b>&#38;#149;</b></font>$file";
}else{
  $right .= "<br><font color='#ff0000'><b>&#38;#149;</b></font>$file";
}

[superkingkong]

thanks for the suggestion

 

i tried to put the code in the particular directory,

 

it only shows the top and bottom row. total files uploaded is only 1.

all the files are not showing. do you know the reason?

 

by the way, the directory is not empty.

 

thanks.

[xtopolis]

Is the path correct?  I changed my $dir to be /upload, not ../upload.

Forgot to change it back before posting, sorry.

[superkingkong]

Is the path correct?  I changed my $dir to be /upload, not ../upload.

Forgot to change it back before posting, sorry.

 

hey, thanks

my bad, too excited to try out the new code, missed the 2 dots

 

thanks again

[superkingkong]

hi,

 

i'm sorry to bother again

 

i've noticed that... although the directory is "empty", the count is showing 1.

 

well, actually, my upload directory has a .htaccess file. is glob reading it as well although it is not declared in glob?

 

thanks.

[superkingkong]

oh, i'm not sure whether it reads the .htaccess.

 

all i know is, when my directory has no files (excluding) .htaccess, the count shows 1

 

if i have abc.gif and .htaccess, the count shows 1

if i have abc.gif and def.jpg and .htaccess, the count shows 2

 

so, i'm not sure what is wrong..

[xtopolis]

Do a print_r($files) and see if it contains anything.