如何在浏览器中实时输出PHP结果

我已经创建了这段代码，它每秒显示下一个整数，但也有错误随着输出。

<?php
ob_implicit_flush();
for ($i = 0; $i < 30; $i++) {
  echo "-> $i <br>'n";
  ob_end_flush();
  ob_end_clean();
  sleep(1);
}
?>

Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush in c:'apache'www'TEST.PHP on line 6
Notice: ob_end_clean(): failed to delete buffer. No buffer to delete in C:'apache'www'TEST.PHP on line 7
-> 4

将@符号放在ob_*函数上以沉默这些错误也会禁用实时输出。