A comprehensive review of PHP code optimization techniques

The purpose of PHP optimization is to spend the least cost in exchange for the fastest running speed and the easiest to maintain code. This article provides you with comprehensive optimization tips.

　1. Echo is faster than print.

　2. Use multiple parameters of echo instead of string concatenation.

　3. Determine the maximum number of loops before executing the for loop. Do not calculate the maximum value every loop. It is best to use foreach instead.

　4. For global variables, they should be unset()ed after use.

　5. Use single quotes instead of double quotes to include strings. This will be faster. Because PHP will search for variables in a string surrounded by double quotes, single quotes will not.

　6. Functions replace regular expressions to complete the same function.

　7. When executing the increment or decrement of variable $i, $i++ will be slower than ++$i. This difference is specific to PHP and does not apply to other languages. ++$i is faster because it only requires 3 instructions (opcodes), while $i++ requires 4 instructions. Post-increment actually creates a temporary variable that is subsequently incremented. Prefix increment increases directly on the original value.

　8. It is better to use a switch case than to use multiple if, else if statements.

　9. Use var_dump to debug PHP code. If you are looking for PHP debugging technology, I must say that var_dump should be the goal you are looking for. This command can meet all your needs in terms of displaying PHP information, and most cases of debugging code are related to getting values ​​in PHP.

　10. Use the full path when including files, and it will take less time to parse the operating system path.

　11. It is a bad practice to create global values ​​​​at every turn, but sometimes the actual situation does require this. It's a good idea to use global values ​​for database table or database connection information, but don't use global values ​​too frequently in your PHP code. Alternatively, a better approach is to store your global variables in a config.php file.

　12. If you want to know the time when the script starts executing, it is better to use $_SERVER[‘REQUEST_TIME’] instead of time().

　13. Open the mod_deflate module of apache.

　14. Using @ to block error messages is very inefficient.

　15. Try to use as many PHP built-in functions as possible.

　16. Incrementing an undefined local variable is 9 to 10 times slower than incrementing a predefined local variable.

　17. Methods in derived classes run faster than the same methods defined in base classes.

　18. Only defining a local variable without calling it in a function will also slow down the speed (to the same extent as incrementing a local variable)

　19. Apache takes longer to parse a PHP script than to parse a static HTML page 2 to 10 times slower. Try to use more static HTML pages and less scripts.

　20. As mentioned before, the most important part of any PHP website is 99% likely to be the database. Therefore, you need to be very familiar with how to use SQL correctly, learn relational tables and more advanced database technologies.

　21. Calling an empty function with one parameter takes the same time as performing 7 to 8 local variable increment operations.

　22. When operating a string and need to check whether its length meets certain requirements, you will naturally use the strlen() function. This function executes quite quickly because it does not do any calculations and just returns the known string length stored in the zval structure (C's built-in data structure used to store PHP variables).

　23. Not all situations must use object-oriented development. Object-oriented development is often very expensive, and each method and object call consumes a lot of memory.

　24. Unless the script can be cached, it will be recompiled every time it is called. Introducing a PHP caching mechanism can usually improve performance by 25% to 100% to eliminate compilation overhead.