PHP Execution Rate Optimization techniques summary _php Skills

1. When you can use file_get_contents instead of file, fopen, feof, Fgets and other series of methods, as far as possible with file_get_contents, because his efficiency is much higher! But pay attention to file_get_contents in opening a URL file when the PHP version problem;

2. As little as possible file operation, although the PHP file operation efficiency is not low;

3. Optimize select SQL statements, as little as possible in the case of INSERT, update operations (on the update, I was a bad batch);

4. Use PHP internal function as much as possible (but I am looking for a function that does not exist in PHP, wasting the time that can write a custom function, experience problem!) ）；

5. Do not declare variables inside the loop, especially large variables: objects (this seems to be not just a matter of note in PHP)? )；


6. Multidimensional arrays as far as possible not to cycle nested assignment;



7. Do not use regular expressions when you can use PHP internal string manipulation functions;



8.foreach more efficient, try to use foreach instead of while and for loops;



9. Use single quotes instead of double quotes to quote strings;



10. Replace i=i+1 with I+=1. In line with the C + + habit, efficiency is also high;



11. For global variables, should be used up on the unset () off;


Statically called members must be defined as static (PHP5 only)

TIPS:PHP5 introduces the concept of static members, which is consistent with the internal static variables of PHP4 functions, but the former is used as a member of a class. Static variables are similar to Ruby's class variables (class variable), and instances of all classes share the same static variable. The static invocation of a non-static member is more efficient than a static call to a static member 50-60%. Mainly because the former will produce e_strict warning, internal also need to do the conversion.

<?php
class Foo {
function Bar () {
Echo ' Foobar ';
}
}
$foo = new Foo;
Instance Way
$foo->bar ();
Static Way
Foo::bar ();
?>

Use class Constants (PHP5 only)

TIPS:PHP5 new functionality, similar to C + + Const.

The benefits of using class constants are:

-Compile-time parsing with no additional overhead

-hash table is smaller, so internal lookup is faster

-Class constants exist only in a specific "namespace", so the hash name is shorter

-More clean code, make debugging more convenient



(temporarily) do not use Require/include_once

Require/include_once will open the target file every time it is invoked!

-If you use an absolute path, PHP 5.2/6.0 does not have this problem

-The new APC cache system has solved this problem

File I/O increased => efficiency reduction

If necessary, you can check whether the file has been require/include.



Do not call meaningless functions

Do not use a function when there is a corresponding constant.

<?php
Php_uname (' s ') = = Php_os;
Php_version () = = Php_version;
Php_sapi_name () = = Php_sapi;
?>
Although not used much, but the efficiency improvement is about 3,500%.



The quickest Win32 check.

<?php
$is _win = Directory_separator = = ' \ ';
?>
-No function

-Win98/nt/2000/xp/vista/longhorn/shorthorn/whistler ... General

-Always available



Time problem (php>5.1.0 only)

How do you know the current time in your software? Simple, "time () time () again, and ask me...".

But it will always call the function, slow.

Now, with $_server[' Request_time ', you don't have to call the function, save it again.



Accelerate PCRE

-For the results that do not need to be saved, use (?:)

This way PHP does not have to allocate memory for the content, province. Efficiency increases by about 15%.

-Can not use the regular, do not have the regular, in the analysis time carefully read the manual "String function" section. Is there a useful function you missed?

For example:

STRPBRK ()

STRNCASECMP ()

Strpos ()/strrpos ()/stripos ()/strripos ()



Accelerate STRTR

If you need to convert all of a single character, use a string instead of an array to do STRTR:

<?php
$ADDR = STRTR ($addr, "ABCD", "efgh"); Good
$ADDR = STRTR ($addr, Array (' A ' => ' e '),
// ...
)); Bad
?>
Efficiency improvement: 10 times times.



Don't make unnecessary substitutions.

Even if there is no substitution, str_replace allocates memory for its parameters. It's slow! Solution:

-Use Strpos to find (very fast) to see if you need to replace, if necessary, replace

Efficiency:

-If you need to replace: the efficiency is almost equal, the difference is about 0.1%.

-If no replacement is needed: Use Strpos fast 200%.



The Evil @ operator

Do not abuse the @ operator. Although the @ looks simple, there are many actions in the background. Use @ compared to the @, efficiency gap: 3 times times.

In particular, do not use @ in the loop, in 5 cycles of testing, even if the first with error_reporting (0) to turn off the error, after the loop is completed and then open, than the @ faster.



Make good use of strncmp

When you need to contrast the "first n characters" is the same time, with strncmp/strncasecmp, rather than Substr/strtolower, is not pcre, let alone ereg. STRNCMP/STRNCASECMP efficiency is highest (though not much).



Careful with Substr_compare (PHP5 only)

According to the above truth, Substr_compare should be faster than the first substr more quickly slightly. The answer is in the negative unless:


-Disregard for case comparison

-Relatively large strings





Do not use constants instead of strings

Why:

-Need to query hash table two times

-Need to convert the constant name to lowercase (when the second query is made)

-Generate E_notice Warning

-Creates a temporary string

Efficiency difference: 700%.





Do not put count/strlen/sizeof in a for-loop conditional statement

Tips: My personal approach

<?php
for ($i = 0, $max = count ($array); $i < $max; + + $i);
?>
Efficiency improvement relative to:

-Count 50%

-Strlen 75%



Short code is not necessarily fast


<?php
Longest
if ($a = = $b) {
$str. = $a;
} else {
$str. = $b;
}
Longer
if ($a = = $b) {
$str. = $a;
}
$str. = $b;
Short
$str. = ($a = = $b $a: $b);
?>
Which one do you think is fast?

Efficiency comparison:

-longest:4.27

-longer:4.43

-short:4.76

Incredible? One more:


<?php
Original
$d = Dir ('. ');
while (($entry = $d->read ())!== false) {
if ($entry = = '. ' | | $entry = = ' ... ') {
Continue
}
}
Versus
Glob ('./* ');
Versus (include. and ...)
Scandir ('. ');
?>
Which one is fast?

Efficiency comparison:

-original:3.37

-glob:6.28

-scandir:3.42

-Original without oo:3.14

-SPL (PHP5): 3.95

Narrator: From then on, it can be seen that PHP5 's object-oriented efficiency has been improved a lot, efficiency and pure function is not much worse.



Improve PHP file access efficiency

When you need to include other PHP files, use the full path, or the relative path that is easy to convert.

<?php
Include ' file.php '; Bad approach
Incldue './file.php '; Good
Include '/path/to/file.php '; Ideal
?>


Maximize

PHP has a lot of extensions and functions available, before implementing a feature, should see if PHP has this functionality? Is there a simpler implementation?

<?php
$filename = "./somepic.gif";
$handle = fopen ($filename, "RB");
$contents = Fread ($handle, FileSize ($filename));
Fclose ($handle);
vs. much simpler
File_get_contents ('./somepic.gif ');
?>





Tips on quoting

References can:

-simplifies access to complex structure data

-Optimize Memory usage


<?php
$a [' B '] [' c '] = array ();
Slow 2 extra hash lookups per access
for ($i = 0; $i < 5; + + $i)
$a [' B '] [' C '] [$i] = $i;
Much faster reference based approach
$ref =& $a [' B '] [' C '];
for ($i = 0; $i < 5; + + $i)
$ref [$i] = $i;
?>
<?php
$a = ' large string ';
Memory Intensive approach
function A ($STR) {
return $str. ' Something ';
}
More efficient solution
Function A (& $STR) {
$str. = ' something ';
}
?>


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Resources

Http://ilia.ws

Ilia's personal website, Blog, his involvement in the development and publication of some manuscript links and so on.

Http://ez.no

EZ Components official website, EZ Comp is aimed at PHP5 open source general-purpose library, to the efficiency of responsibility, Ilia also participated in the development.

Http://phparch.com

Php|architect, a good PHP publisher/training organization. If you can't afford it or can't buy it, there's a lot of classic piracy on the Internet.

Http://talks.php.net

PHP Conference on the collection of speeches, is not very rich, but the content is to let people look at the easy to eat and sleep good dongdong, recommend the morning sleepy dim time or after lunch carefully study, otherwise you will forget to eat and sleeping!