php编程实现追加内容到txt文件中的方法

$filename="aa/a.txt";
$handle=fopen($filename,"w");
$str=fwrite($handle,"test");
fclose($handle);

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$filename="aa/a.txt";
$handle=fopen($filename,"a+");
$str=fwrite($handle,"test\n");
fclose($handle);

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$lines=file("db.txt");
foreach ($lines as $value) {
$line=explode(",",$value);
echo "no1:$line[0]--no2:$line[1]---time:$line[2]-<br>";
}