php optimization

1. 05/19/12 php optimization 1

2.  There are many ways to improve the way you write your PHP
code.
 And we can easily increase the efficiency of our code just by
putting in some effort during development.
 However, there might be some unknown information that you
might not aware in PHP that can help improve your code.
 In php optimization concepts looks more efficient than
other things.
They are followings in next slides,
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3. ECHO VS PRINT:
 Echo is better.
 But how much better?
 Its around 12%-20% faster using echo compare to print
when there is no $ symbol in the printing string.
 And around 40-80% faster if there is an $ symbol used in a
printing string!
SINGLE VS DOUBLE QUOTES:
 Single(’) quote is faster than double(”) quote.
 Why? Because PHP will scan through double quote
strings for any PHP variables (additional operation).
 So unless you have a $var inside the string use single
quotes.
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4. Ex:1
$var = 'I have text';
$var2 = "I have text"; // We dont have vars so single would be good;
$var3 = "I have $var"; // In this case the double quotes is necessary
LOOP:
 Loop is considered as efficiency killer if you have many
nested loop (means loop in a loop) as one loop will required to
run ‘n’ times
 If you have 1 nested loop, this means your program will have
to run n2 times.
 Using a for loop is better than foreach and while loop
if the maximum loop is pre-calculated outside the for
loop!
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5. Ex:2
// For each loop the count function is being called.
for($i =0; $i < count($array);$i++)
{ echo 'This is bad'; }
#Better than foreach and while loop
$total = (int)count($array);
for($i =0; $i < $total;$i++)
{ echo 'This better, max loop was pre-calculated'; }
DOT VS COMMAS CONCATENATION:
$a = '10 PHP programming ';
$b = 'Improvement Tips';
#10 PHP Programming Improvement Tips
echo $a.$b;
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6. The other way is:
$a = 'PHP ';
$b = 'Tips';
echo $a,$b;
 Tests show that dot is more preferable if there are no
variables or $ symbol involved which is around 200% faster.
 On the other hand, commas will help to increase around
20%-35% efficiency when dealing with $ symbols.
PRE INCREMENT VS POST INCREMENT:
 In PHP, it seems like pre increment is better than the
other ways of performing an increment.
 Its around 10% better than post increment? The
reason? Some said that post increment made certain
copy unlike pre increment.
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7. EX:3
$i++;
++$i;
$i+=1;
$i = $i + 1;
EXPLODE VS PREG_SPLIT:
 To split a string the usual way is to use explode because it
support even on PHP4.0. The answer in term of efficiency is
explode.
 Split supports regular express and this makes it quite the
same comparison between str_replace and preg_replace,
anything that have regular expression support will usually be a
bit more slower than those that doesn’t support it.
 It took around 20.563% faster using explode in
PHP.
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8. WHEN CHECKING THE LENGTH OF STRINGS:
Use isset where possible in replace of strlen.
if (!isset($foo{5}))
{ echo "Foo is too short"; }
//is faster than
if (strlen($foo) < 5)
{ echo "Foo is too short"; }
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9. VARIABLES AND FUNCTIONS
 There are some handy things you can do with variables
and functions in php to help optimize your script.
 Unset or null your variables to free memory, especially
large arrays.
Use require() instead of require_once() where possible.
 Use absolute paths in includes and requires. It means less
time is spent on resolving the OS paths.
include('/var/www/html/your_app/test.php');
//is faster than
include('test.php');
 require() and include() are identical in every way
except require halts if the file is missing. Performance
wise there is very little difference.
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10. “else if” statements are faster than “switch/case”
statements.
PHP OPTIMISATION TIPS REVISITED:
 Avoid magic like __get, __set, __autoload.
 Since PHP5, the time of when the script started executing can be
found in $_SERVER[’REQUEST_TIME’], use this instead of time()
or microtime().
 When parsing with XML in PHP try xml2array, which makes use
of the PHP XML functions, for HTML you can try PHP’s
DOM document or DOM XML in PHP4.
 str_replace is faster than preg_replace, str_replace is best
overall, however strtr is sometimes quicker with larger strings.
Using array() inside str_replace is usually quicker than multiple
str_replace. [
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11.  Close your database connections when you’re done with them.
 $row[’id’] is 7 times faster than $row[id], because if you don’t supply
quotes it has to guess which index you meant, assuming you didn’t mean a
constant.
 Use <?php … ?> tags when declaring PHP as all other styles are
depreciated, including short tags.
 When using header(‘Location: ‘.$url); remember to follow it with a
die(); as the script continues to run even though the location has
changed or avoid using it all together where possible.
 Incrementing a local variable in an OOP method is the fastest.
Nearly the same as calling a local variable in a function and
incrementing a global variable is 2 times slow than a local
variable.
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12.  Methods in derived classes run faster than ones defined in the base class.
 If you need to find out the time when the script started executing,
$_SERVER['REQUEST_TIME'] is preferred to time()
 Incrementing an object property (eg. $this->prop++) is 3 times
slower than a local variable.
true is faster than TRUE:
 This is because when looking for constants PHP does a
hash lookup for name as is.
 And since names are always stored lowercased, by
using them you avoid 2 hash lookups.
Furthermore, by using 1 and 0 instead of TRUE and
FALSE, can be considerably faster.
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13. select vs. multi if and else if statements:
 It’s better to use select statements than multi if, else if statements.
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