PHPでファイルを操作するさまざまな方法のまとめ（コード付き）

$filename = "wel.txt";
$fp = fopen($filename, "r");
$data = fread($fp, filesize($filename));
echo $data;
fclose($fp);

$filename = "wel.txt";
$data = file_get_contents($filename, filesize($filename));
echo $data;

$filename = "wel.txt";
$fp = fopen($filename, "rb");
while(!feof($fp)) {    
$line = fgets($fp);
    echo $line.&#39;<br/>&#39;;
}fclose($fp);

$filename = "wel.txt";
readfile($filename);

$filename = "wel.txt";
$fp = fopen($filename, "r");
fpassthru($fp);

$filename = "wel.txt";
$filearray = file($filename);
print_r($filearray);

$filename = "wel.txt";
$content = "xiaoD";
$fp = fopen($filename, "a");
fwrite($fp, $content, strlen($content));
fclose($fp);

$filename = "wel.txt";$content = "xiaoD";
$fp = fopen($filename, "a");
flock($fp, LOCK_EX);
fwrite($fp, $content, strlen($content));
flock($fp, LOCK_UN);
fclose($fp);

$filename = "we2l.txt";
if(file_exists($filename)) {
    readfile($filename);
} else {    
echo 'file not exists';
}

$filename = "we2l.txt";
if(file_exists($filename)) {
    unlink($filename);
} else {    
echo 'file not exists';
}

fseek($fp, 2);

ftell($fp);

rewind($fp);