PHP 10 very practical advanced application skills_PHP tutorial

PHP’s unique syntax mixes C, Java, Perl and PHP’s own innovative syntax. It can execute dynamic web pages faster than CGI or Perl. Compared with other programming languages, dynamic pages made with PHP embed programs into HTML documents for execution, and the execution efficiency is much higher than CGI that completely generates HTML tags. Here are ten advanced PHP application tips.

1. Use the ip2long() and long2ip() functions to convert the IP address into an integer and store it in the database.

This method reduces the storage space to nearly a quarter (15 bytes for char(15) vs. 4 bytes for integer), it is simpler to calculate whether a specific address is within a range page, and Searching and sorting are made faster (although sometimes just a little faster).

2. Use the checkdnsrr() function to verify whether the domain name exists when verifying the email address.

This built-in function confirms that the specified domain name can be resolved to an IP address. The user comments section of the PHP documentation for this function has a simple user-defined function based on checkdnsrr() that verifies the validity of the email address. For the specific usage of this function, you can consult the PHP help documentation.

3. If you are using PHP 5 and MySQL 4.1 or higher, consider abandoning the mysql_* series of functions and using the improved mysqli_* series of functions.

A nice feature is that you can use prepared statements, which can speed up queries if you are maintaining a database-intensive site. This is a conclusion based on some evaluation scores.

4. Learn to love the ternary operator.

5. If you feel that there is a reusable part in the project, check whether it is already in PEAR before you write a line of code.

Many PHP programmers know that PEAR is a good resource library, although many programmers do not. This online resource library contains over 400 reusable program snippets that you can use immediately in your programs. Unless your project is really special, you can always find a PEAR package to save you time. (See PECL)

6. Use highlight_file() to automatically print out beautifully formatted source code.

If you are looking for help with a script on message boards, IRC, etc., this function is very convenient to use. Of course, be careful not to accidentally reveal your database connection information, passwords, etc.

7. Use the error_reporting(0) function to prevent users from seeing potentially sensitive error information.

Ideally, publishing servers should be completely disabled in php.ini. But if you are using a shared web server and you do not have your own php.ini file, then your best option in this case is to add error_reporting(0); (or using require_once() method). This completely blocks sensitive SQL queries and pathnames in the event of an error.

8. Use gzcompress() and gzuncompress() to explicitly compress/decompress strings before storing large strings in the database.

This PHP built-in function uses the gzip algorithm and can compress normal text up to 90%. I use these functions every time I want to read or write a BLOB type field. The only exception is when I need full text search.

9. Get multiple return values ​​from a function by passing parameters by "reference".

Like the ternary operator, this trick is known to most programmers with formal programming training. But those programmers whose HTML background is greater than Pascal's background have more or less asked this question "How to return multiple values ​​​​from a function when return can only be used once?" The answer is to add a before the variable "&" symbol, passed by "reference" instead of "value".

10. Fully understand the dangers of "magic quotes" and SQL injection.

I hope the developers reading this are already familiar with SQL injection. But I still list this here because it is indeed a bit difficult to understand. If you haven't heard of it yet, spend the rest of the day Google, read, and visit PHP Programmer's Notes sites.

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