PHP: What does CURLOPT_URL really do?

Question

I'm new to curl library. Google solves most of my questions such as how to execute a curl. However, there is one thing still confuses me, that is when we set

curl_setopt($ch,CURLOPT_URL,'http://example.com')

will curl download the content from the targeted website? if not, then how curl posts the content? Thanks!

Answer 1

A typical session of curl in PHP looks like this:

// Initialize curl
$ch = curl_init('http://www.google.com');

// Configure curl as needed, depending on your application
curl_setopt_array($ch, array(
    'CURLOPT_FOLLOWLOCATION' => TRUE,
    'CURLOPT_RETURNTRANSFER' => TRUE,
    'CURLOPT_CONNECTTIMEOUT' => 3,
    // ... other options here ...
));

// Do the request
$page = curl_exec($ch);

// Cleanup
curl_close($ch);

Sometimes you may want to do several requests using the same options. For subsequent requests you can repeat the code above with a different URL (or encapsulate it in a function for convenience).

Or you can reuse the existing resource and issue multiple requests before closing it.

To do this call curl_setopt($ch, CURLOPT_URL, 'http://example.com') to change the URL then call curl_exec() again to get the new page.

Repeat these two steps as many times as you need before calling curl_close() .

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To answer your question, curl_setopt() and curl_setopt_array() only prepare the curl object and the HTTP request. curl_exec() is the function that actually sends the request and returns (or displays) the content it receives.