Four ways to access url in php

//访问指定URL函数
function access_url($url) {    
    if ($url=='') return false;    
    $fp = fopen($url, 'r') or exit('Open url faild!');    
    if($fp){  
    while(!feof($fp)) {    
        $file.=fgets($fp)."";  
    }  
    fclose($fp);    
    }  
    return $file;  
}

$content = file_get_contents("http://www.google.com");

function curl_file_get_contents($durl){  
    $ch = curl_init();  
    curl_setopt($ch, CURLOPT_URL, $durl);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true) ; // 获取数据返回    
    curl_setopt($ch, CURLOPT_BINARYTRANSFER, true) ; // 在启用 CURLOPT_RETURNTRANSFER 时候将获取数据返回    
    $r = curl_exec($ch);  
    curl_close($ch);  
    return $r;  
}

$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);     
if (!$fp) {     
    echo "$errstr ($errno)<br />\n";     
} else {     
    $out="GET / HTTP/1.1\r\n";     
    $out.="Host: www.example.com\r\n";     
    $out.="Connection: Close\r\n\r\n";     
    fwrite($fp, $out);     
    while (!feof($fp)) {     
        echo fgets($fp, 128);     
    }  
    fclose($fp);     
}