$handle = fopen(string $filename, string $mode, bool $use_include_path = false, resource $context = null)

// 读取文件
$file = fopen("example.txt", "r") or die("无法打开文件!");
while(!feof($file)) {
    echo fgets($file)."<br>";
}
fclose($file);

// 写入文件
$file = fopen("newfile.txt", "w") or die("无法打开文件!");
$txt = "Hello World\n";
fwrite($file, $txt);
fclose($file);

mixed str_replace(mixed $search, mixed $replace, mixed $subject, int &$count = null)

// 简单替换
$str = "Hello world!";
echo str_replace("world", "PHP", $str); // 输出: Hello PHP!

// 数组替换
$search = array("Hello", "world");
$replace = array("Hi", "PHP");
echo str_replace($search, $replace, "Hello world!"); // 输出: Hi PHP!

// 统计替换次数
$count = 0;
str_replace("l", "L", "Hello world!", $count);
echo $count; // 输出: 3

// 读取文件内容并替换特定字符串
$filename = "template.html";
$file = fopen($filename, "r") or die("无法打开文件!");
$content = fread($file, filesize($filename));
fclose($file);

// 替换模板变量
$replacements = array(
    "{TITLE}" => "我的网页",
    "{CONTENT}" => "这是主要内容区域",
    "{FOOTER}" => "版权所有 © 2023"
);

$newContent = str_replace(array_keys($replacements), array_values($replacements), $content);

// 写入新文件
$newFile = fopen("output.html", "w") or die("无法创建文件!");
fwrite($newFile, $newContent);
fclose($newFile);