If you encounter a problem, you need to close it. Three problems encountered when debugging a PHP program.

1. The filesize() function returns an incorrect value.
When using curl to download a page locally, you need to read the contents of the downloaded temporary file tmpHtml.txt into a buffer. Since I use fread() to read, I need to pass in the size to be read, so I first use filesize(‘./tmpHtml.txt’) to get the temporary file size. The weird thing is that the size of the temporary file obtained is incorrect. I set a breakpoint to debug and manually search for the file on the hard disk after calling filesize(). The file size is different from the result obtained by filesize().
Search filesize on php.net, and you can see this sentence in the function description: Note: The results of this function will be cached. See clearstatcache() for more details.
Check clearstatcache() again, and I found the reason:
PHP will cache the return information of these (function tables are provided for query) functions to provide faster performance. In some cases, however, you may want to clear cached information. For example, if you check the same file multiple times in a script and the file is in danger of being deleted or modified during the execution of the script, you need to clear the file status cache. In this case, you can use the clearstatcache() function to clear the file information cached by PHP.
2. In a UTF-8 encoded PHP script, how to match Chinese when pattern matching GBK encoded Chinese web content.
In yesterday's development, we needed to match content containing the GBK encoded string 'Apple', so we wrote the following code:

Copy the code The code is as follows:

$pat = '//';
$pat = iconv('UTF-8', 'GB2312', $pat);
$ret = preg_match_all($pat, $contents, $matches);

It’s life or death There was no match, so I tried to convert the content to UTF-8 encoding first, as follows:

Copy the code The code is as follows:

$pat = '//' ;
$contenst = iconv('GB2312', 'UTF-8', $contents);
$ret = preg_match_all($pat, $contents, $matches);

So it will match. But I can’t figure it out, and I suspect there’s some fraud involved.
But the tragedy is that I used the first method again today and got matched again. It seems the problem lies elsewhere.
Ah! I am a pig, problem 2 is caused by problem 1! The filesize() is obtained incorrectly, so naturally it cannot be matched! The second method is matched after solving problem 1!
3. Why is the download address of the quote image obtained by inspecting the element in the browser different from the download address obtained by curl.
Maybe...the final answer is still: I am a pig.
Because the URI object is: attachment.php? aid=Mzk3MTB8YTg5ZTYyNTJ8MTMyNjcyNDEwMXw5NWYydC9aOUE0a05EVm9ydlErSFBRamZJNWJQL1NHdWJLK3ZraU9GTDZYdnBUdw%3D%3D¬humb=yes
What is aid? It's probably something related to session, and it's normal for it to change. Later, it was no problem to capture something that looked like a static path.
The above three stories contain two tragedies. These are stupid mistakes that PHP beginners must make.

The above introduces the three problems encountered when debugging a PHP program that need to be closed when encountering a problem, including the content that needs to be closed when encountering a problem. I hope it will be helpful to friends who are interested in PHP tutorials.