php php读取文件

<?php
$file = fopen("example.txt", "r") or exit("Unable to open file!");
while(!feof($file)) {
    echo fgets($file). "<br>";
}
fclose($file);
?>

<?php
$content = file_get_contents("example.txt");
echo $content;
?>

<?php
$file = new SplFileObject("example.txt");
while (!$file->eof()) {
    echo $file->fgets();
}
?>

<?php
if (file_exists("example.txt")) {
    $file = fopen("example.txt", "r") or exit("Unable to open file!");
    while(!feof($file)) {
        echo fgets($file). "<br>";
    }
    fclose($file);
} else {
    echo "File does not exist.";
}
?>

<?php
if (is_readable("example.txt")) {
    $file = fopen("example.txt", "r") or exit("Unable to open file!");
    while(!feof($file)) {
        echo fgets($file). "<<br>";
    }
    fclose($file);
} else {
    echo "File is not readable.";
}
?>

<?php
$file = fopen("large_example.txt", "r") or exit("Unable to open file!");
while(!feof($file)) {
    echo fread($file, 1024); // 每次读取1024字节
}
fclose($file);
?>