Collection of PHP code optimization_PHP tutorial

A collection of PHP code optimizations

1. If a method can be static, declare it as static, and the speed can be increased by 1/4;

2. Echo is more efficient than print because echo does not return a value and print returns an integer;

3. Set the maximum number of loops before the loop, not during the loop;

4. Destroy variables to release memory, especially large arrays;

5. Avoid using magic methods like __get, __set, __autoload, etc.;

6.requiere_once() consumes more resources;

7. Use absolute paths in includes and requires

8. If you need to get the time when the script is executed, $_SERVER['REQUSET_TIME'] is better than time();

9. If you can use character processing functions, try to use them because they are more efficient than regular expressions;

10.str_replace character replacement is faster than regular replacement preg_replace, but strtr is 1/4 faster than str_replace;

11. If a function can accept both arrays and simple characters as parameters, such as character replacement, and the parameter list is not too long, you can consider using more concise replacement statements to only replace one character at a time instead of accepting Arrays as search and replace parameters. Make big things small, 1+1>2;

12. Covering errors with @ will slow down the running speed of the script;

13.$row['id'] is 7 times faster than $row[id]. It is recommended to develop the habit of adding quotes to array keys;

14. Error messages are very useful;

15. Don’t use functions in loops, such as For($x=0; $x < count($array); $x), the count() function calculates first outside;

16. Creating local variables in a method is the fastest, almost as fast as calling local variables in a method;

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17. Creating a global variable is 2 times slower than a local variable;

18. Creating an object property (a variable in a class) such as ($this->prop++) is 3 times slower than a local variable;

19. Creating an undeclared local variable is 9-10 times slower than an initialized local variable;

20. Declaring a global variable that has not been used by any function will also reduce performance (the same as declaring the same number of local variables). PHP may check whether the global variable exists;

　21. The performance of a method has nothing to do with the number of methods defined in a class, because there is no performance difference after I add 10 or more methods to the tested class (these methods are before and after the test method);

22. The performance of methods in subclasses is better than that in base classes;

23. The time it takes to run a function that calls only one parameter and has an empty function body is equal to 7-8 $localvar++ operations, while a similar method (function in a class) runs equal to about 15 $localvar++ operations;

　24.Surrounding your string by ' instead of ” will make things interpret a little faster since php looks for variables inside “…” but not inside ‘…’. Of course you can only do this when you don't need to have variables in the string.

25. It is faster to use commas instead of dots when outputting strings. Note: This only works for echo, this function can accept some strings as parameters;

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26. In the apache server, 2nxx a php script page takes at least 2-10 times more time to generate than the corresponding HTML static page. It is recommended to use more static HTML pages and a few steps;

27. Unless you have a cache installed, your php script needs to be recompiled every time it is accessed. It is recommended to install a php cache program, which can significantly improve your performance by 20-100% by removing some repeated compilation;

28. It is recommended to use memcached, a high-performance distributed memory object caching system, to improve the performance of dynamic network applications and reduce the burden on the database;

29. Use the ip2long() and long2ip() functions to convert the IP address into an integer and store it in the database instead of a character. This reduces storage space by almost 1/4. At the same time, addresses can be easily sorted and quickly searched;

30. Use checkdnsrr() to confirm the validity of some email addresses through the existence of domain names. This built-in function can ensure that each domain name corresponds to an IP address;

31. If you are using php5 and mysql4.1 or above, consider using the improved function mysqli_* of mysql_*;

　32. Try using the ternary operator (?:);

33. Before you think about completely redoing your project, see if PEAR has what you need. PEAR is a huge resource library that many PHP developers know;

34. Use highlight_file() to automatically print a well-formatted copy of the page source code;

　35. Use the error_reporting(0) function to prevent potentially sensitive information from being displayed to the user. Ideally error reporting should be completely disabled in the php.ini file. But if you are using a shared virtual host and you cannot modify php.ini, then you'd better add the error_reporting(0) function and put it on the first line of each script file (or use require_once() to load it). This can Effectively protect sensitive SQL queries and paths from being displayed when errors occur; ofAdmin.Com

　36. Use gzcompress() and gzuncompress() to compress (decompress) large-capacity strings when storing (retrieving) the database. This built-in function can compress up to 90% using the gzip algorithm;

37. Make a function have multiple return values ​​by referencing the parameter variable address. You can add an "&" before the variable to indicate passing it by address rather than by value;

　38.Fully understand “magic quotes” and the dangers of SQL injection. I'm hoping that most developers reading this are already familiar with SQL injection. However, I list it here because it's absolutely critical to understand. If you' ve never heard the term before, spend the entire rest of the day googling and reading.

39. Using strlen() is not very fast because it needs to call some other operations such as lowercase and hash table queries. We can use isset() to achieve similar functions. isset() is faster than strlen();

　40.When incrementing or decrementing the value of the variable $i++ happens to be a tad slower then ++$i. This is something PHP specific and does not apply to other languages, so don't go modifying your C or Java code thinking it'll suddenly become faster, it won't. ++$i happens to be faster in PHP because instead of 4 opcodes used for $i++ you only need 3. Post incrementation actually causes in the creation of a temporary var that is then incremented. While pre-incrementation increases the original value directly. This is one of the optimization that opcode optimized like Zend's PHP optimizer. It is a still a good idea to keep in mind since not all opcode optimizers perform this optimization and there are plenty of ISPs and servers running without an opcode optimizer.

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