Tips to optimize the php script.....
Suggestion for exception handling in php...



Tips to optimize the php script..... Suggestion for exception handling in php.....

Answer / modi[achir communication]

1. If a method can be static, declare it static. Speed
improvement is by a factor of 4.

2. echo is faster than print.

3. Set the maxvalue for your for-loops before and not in the
loop.

4. Unset your variables to free memory, especially large arrays.

5. Avoid magic like __get, __set, __autoload

6. require_once() is expensive

7. Use full paths in includes and requires, less time spent
on resolving the OS paths.

8. If you need to find out the time when the script started
executing, $_SERVER[�REQUEST_TIME�] is preferred to time()

9. See if you can use strncasecmp, strpbrk and stripos
instead of regex

10. str_replace is faster than preg_replace, but strtr is
faster than str_replace by a factor of 4

11. If the function, such as string replacement function,
accepts both arrays and single characters as arguments, and
if your argument list is not too long, consider writing a
few redundant replacement statements, passing one character
at a time, instead of one line of code that accepts arrays
as search and replace arguments.

12. Error suppression with @ is very slow.

13. $row[�id�] is 7 times faster than $row[id]

14. Error messages are expensive

15. Do not use functions inside of for loop, such as for
($x=0; $x < count($array); $x) The count() function gets
called each time.

16. Incrementing a local variable in a method is the
fastest. Nearly the same as calling a local variable in a
function.

17. Incrementing a global variable is 2 times slow than a
local var.

18. Incrementing a object property (eg. $this->prop++) is 3
times slower than a local variable.

19. Incrementing an undefined local variable is 9-10 times
slower than a pre-initialized one.

20. Just declaring a global variable without using it in a
function also slows things down (by about the same amount as
incrementing a local var). PHP probably does a check to see
if the global exists.

21. Method invocation appears to be independent of the
number of methods defined in the class because I added 10
more methods to the test class (before and after the test
method) with no change in performance.

22. Methods in derived classes run faster than ones defined
in the base class.

23. A function call with one parameter and an empty function
body takes about the same time as doing 7-8 $localvar++
operations. A similar method call is of course 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. When echoing strings it's faster to separate them by
comma instead of dot. Note: This only works with echo, which
is a function that can take several strings as arguments.

26. A PHP script will be served at least 2-10 times slower
than a static HTML page by Apache. Try to use more static
HTML pages and fewer scripts.

27. Your PHP scripts are recompiled every time unless the
scripts are cached. Install a PHP caching product to
typically increase performance by 25-100% by removing
compile times.

28. Use memcached - memcached is a high-performance memory
object caching system intended to speed up dynamic web
applications by alleviating database load

29. Use ip2long() and long2ip() to store IP addresses as
integers instead of strings in a database. This will reduce
the storage space by almost a factor of four (15 bytes for
char(15) vs. 4 bytes for the integer), make it easier to
calculate whether a certain address falls within a range,
and speed-up searches and sorts (sometimes by quite a bit).

30. Partially validate email addresses by checking that the
domain name exists with checkdnsrr(). This built-in function
checks to ensure that a specified domain name resolves to an
IP address. A simple user-defined function that builds on
checkdnsrr() to partially valid email addresses can be found
in the user comments section in the PHP docs. This is handy
for catching those occasional folks who think their email
address is &#65533;joeuser@wwwphp.net&#65533; instead of &#65533;joeuser@php.net&#65533;.

31. If you&#65533;re using PHP 5 with MySQL 4.1 or above, consider
ditching the mysql_* functions for the improved mysqli_*
functions. One nice feature is that you can use prepared
statements, which may speed up queries if you maintain a
database-intensive website. Some benchmarks.

32. Learn to love the ternary operator.

33. If you get the feeling that you might be reinventing the
wheel during a project, check PEAR before you write another
line. PEAR is a great resource that many PHP developers are
aware of, yet many more are not. It&#65533;s an online repository
containing over 400 reusable snippets that can be dropped
right into your PHP application. Unless your project is
trully unique, you ought to be able to find a PEAR package
that saves at least a little time. (Also see PECL)

34. Automatically print a nicely formatted copy of a page&#65533;s
source code with highlight_file().This function is handy for
when you need to ask for some assistance with a script in a
messageboard, IRC, etc. Obviously, some care must be taken
not to accidently show your source when it contains DB
connection information, passwords, etc.

35. Prevent potentially sensitive error messages from being
shown to users with the error_reporting(0) function. Ideally
error reporting should be completely disabled on a
production server from within php.ini. However if you&#65533;re on
a shared webhost and you aren&#65533;t given your own php.ini, then
your best bet is to add error_reporting(0); as the first
line in each of your scripts (or use it with
require_once().) This will prevent potentially sensitive SQL
queries and path names from being displayed if things go awry.

36. Use gzcompress() and gzuncompress() to transparently
compress/decompress large strings before storing them in a
database. These built-in functions use the gzip algorithm
and can compress plaintext up to 90%. I use these functions
almost everytime I read/write to a BLOB field within PHP.
The only exception is when I need full text indexing
capabilities.

37. Return multiple values from a function with &#65533;by
reference&#65533; parameters. Like the ternary operator, most PHP
developers who come from a more formalized programming
background already know this one. However, those who&#65533;s
background is more HTML than Pascal, probably have wondered
at one time &#65533;how do I get multiple values back from a
function I wrote, even though I can only use one return
value?&#65533; The answer is that you precede a variable with &#65533;&&#65533;
and use it &#65533;by reference&#65533; instead of &#65533;by value&#65533;.

38. Fully understand &#65533;magic quotes&#65533; and the dangers of SQL
injection. I&#65533;m hoping that most developers reading this are
already familiar with SQL injection. However, I list it here
because it&#65533;s absolutely critical to understand. If you&#65533;ve
never heard the term before, spend the entire rest of the
day googling and reading.

39. When working with strings and you need to check that the
string is either of a certain length you'd understandably
would want to use the strlen() function. This function is
pretty quick since it's operation does not perform any
calculation but merely return the already known length of a
string available in the zval structure (internal C struct
used to store variables in PHP). However because strlen() is
a function it is still somewhat slow because the function
call requires several operations such as lowercase &
hashtable lookup followed by the execution of said function.
In some instance you can improve the speed of your code by
using a isset() trick.

Ex.
if (strlen($foo) < 5) { echo "Foo is too short"; }
vs.
if (!isset($foo{5})) { echo "Foo is too short"; }

Calling isset() happens to be faster then strlen() because
unlike strlen(), isset() is a language construct and not a
function meaning that it's execution does not require
function lookups and lowercase. This means you have
virtually no overhead on top of the actual code that
determines the string's length.

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.

41. Excellent Article about optimizing php by John Lim
http://phplens.com/lens/php-book/opt...ugging-php.php


For Exception Handling see these links:
http://www.andreashalter.ch/phpug/20040115/index.html#what

http://www.devshed.com/c/a/PHP/Error-Handling-in-PHP-Introducing-Exceptions-in-PHP-5/

http://www.w3schools.com/php/php_exception.asp

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