Why does yours have a horizontal line?
There are horizontal lines because this function will be eliminated and is not recommended.
It will be gradually replaced by mysqli_connect and pdo in the future.
It proves that the function you are using is not officially approved for use, that is, it is a function that has been abandoned by the official. You can see it by moving your mouse over the function
This should be a style problem in your editor, right?
Besides, this line should be called strikethrough.
Does this horizontal line mean something different from the sentence without a horizontal line?
Horizontal line?
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
There are horizontal lines because this function will be eliminated and is not recommended.
It will be gradually replaced by mysqli_connect and pdo in the future.
It proves that the function you are using is not officially approved for use, that is, it is a function that has been abandoned by the official. You can see it by moving your mouse over the function
This should be a style problem in your editor, right?
Besides, this line should be called strikethrough.
Horizontal line?