headers already sent

[robin01]

hello,
learning to write a classified script and i'm lost at fixing the following problem.

receiving the following message:
Warning: Cannot modify header information - headers already sent by (output started at /var/www/classified/header.php:24) in /var/www/classified/utility.inc.php on line 35

message appearswhen random_ad_display(function) -> resizeimage(function) is called.

the header.php, is just a title/description of the program and no reference to header found in the header.php script. basic as basic can be.

the following functions are located in utility.inc.php script.

random_ad_display - displays image in a random order in a table.
resizeimage($image1) - resize the image to display in the table.

function random_ad_display($feature_result)
{   echo "<table width='500' align='center' border='0' cellspacing='0' cellpadding='0'>";
    echo "<tr>";
    $i = 0;
    while($row1 = mysql_fetch_array($feature_result))
    {   if ($i == 2)
        {  echo "</tr>";
           echo "<tr>";
             $image1 =  "images/".$row1["cf_images"];
             $test = resizeimage($image1);
          // echo "<td width='250' height='120'> <div align='center'> <p align='center'><IMG SRC='images/" . $image1 . "'width='150' height='120' /></p> <p>description and ad number</p></td>";
           echo "<td width='250' height='120'> <div align='center'> <p align='center'><IMG SRC='" . $test . "'></p> <p>description </p></td>";
           $i = 0;
        }
        else
        {  $image2 = $row1["cf_images"];
           echo "<td width='250' height='120'> <div align='center'> <p align='center'><IMG SRC='images/". $image2 . "' width='150' height='120' /> </p> <p> test description 2 testing one two three four five </p></td>"; }
        $i++;
    }
    echo "</tr>";
    echo "</table>";
}

/***********************************************************************/
function resizeimage($image1)
{   // The file
    $filename = $image1;
    // Set a maximum height and width
    $width = 140;
    $height = 140;
    // Content type
    header('Content-type: image/jpeg');
    // Get new dimensions
    list($width_orig, $height_orig) = getimagesize($filename);
    $ratio_orig = $width_orig/$height_orig;
    if ($width/$height > $ratio_orig)
    {  $width = $height*$ratio_orig;}
    else
    {      $height = $width/$ratio_orig;  }
    // Resample
    $image_p = imagecreatetruecolor($width, $height);
    $image = imagecreatefromjpeg($filename);
    imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);
    // Output
    imagejpeg($image_p, null, 100);
}

any help you can help me would be greatly appreciated.
thanks

[NogDog]

From the error message, it would appear that line 24 of header.php is causing some output to be sent to the client. Once the first output is sent (even if it's just empty lines), headers are sent, and you can no longer use the header() function (or any other function that affects HTTP headers).

[scross]

This line in your "utility.inc.php" script is the problem:

$test = resizeimage($image1);

When you wish to display images from a php script you cannot simply output the image, because it is then inside a html document and is therefore considered as text data and not as an image. PHP reports an error when you try to use the header function to identify your images as images because you cannot have any output before you send a header. You seem to have an idea of the solution to this problem through your use of the <img> tag, however, you are using the variable $test for the file name which has no value because your function resizeimage() doesn't return anything.

I believe what you're trying to do is to resize the image before you display it, so you need to change your resizeimage() function to save the resized image rather than outputting it and then return the file name of the resized image to the random_ad_display(). In order to save the output of your resizeimage() function just change:

imagejpeg($image_p, null, 100);

to

imagejpeg($image_p, $new_file_name, 100);

...obviously setting $new_file_name as your new resized image file name.

Also remember to remove the header() function call and at the end of the resizeimage() function return the new file name ($new_file_name). As long as there are no other errors in your script then that should work fine.