Some key points for PHP newcomers to quickly improve program efficiency

Execution efficiency is the benchmark for measuring code quality, and there are many ways to optimize execution efficiency. Today we will explain how to optimize the execution efficiency of our program from the programming details.

Use single quotes instead of double quotes to enclose the string, which is faster. Because PHP will search for variables in a string surrounded by double quotes, single quotes will not. Note: only echo can do this, it is a "function" that can take multiple strings as parameters (Annotation: PHP Manual It is said that echo is a language structure, not a real function, so the function is enclosed in double quotes).

1. If you can define a class method as static, try to define it as static, and its speed will increase by nearly 4 times.

2. The speed of $row[’id’] is 7 times that of $row[id].

　3. Echo is faster than print, and uses multiple parameters of echo (annotation: refers to using commas instead of periods) instead of string concatenation, such as echo $str1, $str2.

4. 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.

　5. Unregister unused variables, especially large arrays, to free up memory.

6. Try to avoid using __get, __set, __autoload.

7. require_once() is expensive.

8. Try to use absolute paths when including files, because it avoids the speed of PHP searching for files in include_path, and the time required to parse the operating system path will be less.

　9. If you want to know the time when the script starts executing (annotation: that is, the server receives the client request), it is better to use $_SERVER[‘REQUEST_TIME’] than time().

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

　11. The str_replace function is faster than the preg_replace function, but the strtr function is four times more efficient than the str_replace function.

　12. If a string replacement function accepts arrays or characters as parameters, and the parameter length is not too long, you can consider writing an additional replacement code so that each parameter passed is one character instead of Just write one line of code to accept arrays as parameters for query and replace.

13. It is better to use a selective branch statement (translation annotation: switch case) than to use multiple if, else if statements.

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

　15. Opening the mod_deflate module of apache can improve the browsing speed of web pages.

　16. The database connection should be closed when finished using it. Do not use long connections.

　17. Error messages are expensive.

　18. Increasing local variables in a method is the fastest. Almost as fast as calling local variables in a function.

　19. Incrementing a global variable is 2 times slower than incrementing a local variable.

　20. Incrementing an object property (such as: $this->prop++) is 3 times slower than incrementing a local variable.

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