Efficient Programming: Introduction to PHP Optimization Guidelines

What this article brings to you is about high-efficiency programming: PHP optimization guidelines, which have certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

• Use less regular expressions

##str_replace Function is better than preg_replace Much faster, strtr function is faster than str_replace .

strpbrk()、strncasecmp()、strpos()、strrpos()、stripos()、strripos()。

• Character replacement

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

In addition, do not make unnecessary substitutions. Even if there is no substitution, str_replace will allocate memory for its parameters. very slow!

Use strpos to search first (very fast) to see if it needs to be replaced, and if so, replace it.

If replacement is needed, the efficiency is almost the same, and the difference is about 0.1%.

If no replacement is needed: use strpos 200% faster.

• Use the $_SERVER variable

If you need to get the script execution time,

$_SERVER[' REQUSET_TIME']

is better than time(). One is ready-made and can be used directly, and the other requires the result obtained by the function.

• Use

  $iIncrement

when executing the variable# When ##$i

increases or decreases,

$i will be slower than $i. This difference is specific to PHP and does not apply to other languages, so please don't modify your C or Java code and expect it to be instantly faster, it won't work.

$i

is faster because it only requires 3 instructions (opcodes), while

$i requires 4 instructions.

Compress large strings

• Use gzcompress() and gzuncompress() to compress large-capacity strings Compress and decompress, and then
store and take out the database

.

This built-in function uses the gzip algorithm and can compress strings 90%

.

Read file contents

• You can use file_get_contents() instead
file()

,

fopen(), feof(), fgets() and other series of methods, try to use file_get_contents().

echo output

• echo string uses
comma

instead of dot connector to make it faster .

Although, echo

is a language structure, not a real function.

However, it can pass multiple strings separated by commas as "function" parameters, so it will be faster.

autoload and poorly designed autoloading functions will lead to a reduction in its efficiency.

So, try to avoid using magic methods such as __autoload

, which are subject to discussion

Block sensitive information

• Use the error_reporting() function to prevent potentially sensitive information from being displayed to the user.

Ideally error reporting should be completely disabled in the php.ini file.

If you are using a shared virtual host, php.ini cannot be modified, it is best to add the error_reporting() function.

Put it in the first line of each script file, or use

require_once()

to load it, which can effectively protect sensitive SQL queries and paths from being displayed when errors occur

Pure PHP code without end tag

• If the file content is pure PHP code, it is best to delete PHP at the end of the file End tag
?>

.

This can avoid that if spaces or newlines are accidentally added after the PHP end tag, PHP will start to output these spaces, and there is no intention to output them in the script at this time.

Never use
• register_globals

  and magic quotes

  this They are two very old functions, which may have been a good method at the time (ten years ago), but it seems not to be the case now.

Older versions of PHP will turn on these two functions by default during installation, which can cause security vulnerabilities, programming errors and other problems.

For example, variables will only be created when the user inputs data.

Both functions have been abandoned since PHP5.4.0, so every programmer should avoid using them.

If your past programs have used these two functions, remove them as soon as possible.

Use absolute paths

• in
include

and

require Try to use absolute paths. If a relative path is included, PHP will traverse to find the file in include_path

. Using absolute paths will avoid such problems and will take less time to resolve the path.

Try not to use require_once and include_once to include files. They have an additional process of determining whether the file is referenced. Try not to use it if possible.

Use the require and include methods instead.

• Functions are faster than class methods

#Calling a function with only one parameter and an empty function body costs Time is equal to 7-8 times $localvar operations.

The class method with the same function requires about 15 $localvar operations.

• Use subclass methods

#Only put reusable methods in the base class, try to put other functions in the subclass Implemented in a class, the performance of the method in the subclass is better than that in the base class.

• Pass parameters by reference

#Realize multiple return values ​​​​of the function through parameter address reference, which is better than passing parameters by reference Value transfer is efficient. The method is to add & before the parameter variable.

• Make it as static as possible

If a method can be static, declare it as static, the speed can be Improved 1/4, even when I tested, this improved nearly three times.

The main difference in efficiency between static and non-static methods is memory. Static methods generate memory when the program starts, and instance methods (non-static methods) generate memory while the program is running.

So, static methods can be called directly, while instance methods must first create an instance and then call them. Static methods are very fast, but too many methods will occupy memory.

Any language operates on memory and disk. As for whether it is object-oriented, it is just a question of the software layer. The bottom layer is the same, but the implementation method is different.

Static memory is continuous because it is generated at the beginning of the program, while instance methods apply for discrete space, so of course it is not as fast as static methods.

Static methods always call the same memory. The disadvantage is that they cannot be automatically destroyed, but instantiation can be destroyed.

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