What are the methods for downloading network images in PHP?

function dlfile($file_url, $save_to)
{
 $content = file_get_contents($file_url);
 file_put_contents($save_to, $content);
}

function dlfile($file_url, $save_to)
{
 $ch = curl_init();
 curl_setopt($ch, CURLOPT_POST, 0); 
 curl_setopt($ch,CURLOPT_URL,$file_url); 
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
 $file_content = curl_exec($ch);
 curl_close($ch);
 $downloaded_file = fopen($save_to, 'w');
 fwrite($downloaded_file, $file_content);
 fclose($downloaded_file);
}

function dlfile($file_url, $save_to)
{
 $in=  fopen($file_url, "rb");
 $out=  fopen($save_to, "wb");
 while ($chunk = fread($in,8192))
 {
 fwrite($out, $chunk, 8192);
 }
 fclose($in);
 fclose($out);
}