Automatically Upload Images with PHP Directly from the URI

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It is a simple task to upload images on the server with PHP using a simple web form. Than everything’s in the $_FILES array and after submitting the form the file’s on the server. By simply move_uploaded_file you can change its location on the server to the desired folder.

However is there a way to “upload” files without using a web form, but only by telling the PHP script where to find the image. First and most important the image should be web visible and accessible by HTTP.

The solution is quite easy – you can grab the file using file_get_contents, and than put it on the desired server folder with file_put_contents. Here’s some source:

$image = file_get_contents('http://www.example.com/image.jpg');
file_put_contents('/var/www/my.jpg', $image);

Extending the Case

You can go even further by downloading any kind of files with the same approach. What will be the case for an mp4 video is shown in the next example:

$video = file_get_contents('http://www.example.com/video.mp4');
file_put_contents('/var/www/my.mp4', $video);

Usage

This can be quite useful when trying to automate an remote upload process. In this case when somebody uploads an image on his site, you can duplicate this file on your server! However don’t forget the copyrights!

HTTP POST with PHP without cURL

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Awesome PHP

a great php idea!
It’s strange how powerful PHP can be. There’s a legend that cURL is the only way to perform a HTTP POST with PHP, but that isn’t the truth. An extremely useful script is by using stream_context_create:

$optional_headers = null;
$params = array('http' => array(
                'method' => 'POST',
                'content' => http_build_query(array('name' => 'my-name'))));
 
if ($optional_headers !== null) {
    $params['http']['header'] = $optional_headers;
}
 
$ctx = stream_context_create($params);
$fp = @fopen('http://example.com/post.php', 'rb', false, $ctx);

Well this is only a snippet. You can change a lot this code and perform any request, but here’s a small start up. However note that this will do the same as while posting to example.com/post.php via web form!

The Better Way to Unset Variables in PHP

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Don’t know why, but most of times I see the PHP unset() multilined with a only one parameter!?

unset($var1);
unset($var2);
unset($var3);

But as you can see from the PHP doc page of unset() this method takes optional parameter count.

void unset(mixed $var [, mixed $var [, mixed $...]])

So perhaps a better solution can be:

unset($var1, $var2, $var3);

It’s at least single lined!

Friday Algorithms: Input Data and Complexity

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Size of ..

As we all know most of the cases a program execution time depends most from the input data. As I wrote in my post the degree of the input data estimates the algorithm complexity.

Of course 3*n² is a bit faster than 5*n², but in general both functions are similar and have the same complexity. In this case we tend to say that the size of the input data is n.

Size of the input data
The size of the input data affects the complexity of the algorithm

It is easy to bind this to arrays or other simple data structures. For example when sorting an array with n elements, the size of the input data is n, but sometimes there is not such an obvious relation between an algorithm and the size of the input data.

For instance when we’ve to search a path into a graph, than maybe the best way to describe the input data is by summing both the number of vertices and the number of edges.

Conclusion

Think, think, think
Think, think, think

However this is important when dealing with algorithms, because a mistake in the estimation of the input data size will result in wrong algorithm estimation at all

PHP: What is More Powerful Than list() – Perhaps extract()

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list() in PHP

Recently I wrote about list() in PHP which is indeed very powerful when assigning variable values from array elements.

$a = array(10, array('here', 'are', 'some', 'tests'));
list($count, $list) = $a;

Actually my example in the post was not correct, because I wrote that you can pass an associative array, but the truth is that you cannot, and thus the array should be always with numeric keys. After noticing the comments of that post, and thanks to @Philip,  I searched a bit about how this problem can be overcome.

There is a Solution

As always PHP gives a perfect solution! You can see on the list() doc page that there is a function that may help you use an associative array.

Extract

extract() is perhaps less known than list(), but it does the right thing!

$a = array('count' => 10, 'list' => array('here', 'are', 'some', 'tests'));
extract($a);
 
echo $count;    // 10
print_r($list); // array('here'....

Note that now both $count and $list are defined.