PHP Developer / Blog

The previous article in this series talked about how to set PHP up so that it’s a lean mean processing machine. Now we get to make sure that our PHP code follows suit.

Also read part 1 of this article.

I’ll cover 10 lesser known PHP functions or methods that can help streamline your PHP code.

Casting variables is fast
PHP internally casts a variable when it’s value is set. This is why you generally don’t want to $age = ‘10′;. By doing so you’re explicitly telling PHP that $age is a string. There are still times when you will want to explicitly cast a variable after it’s already been set. PHP provides numerous functions to do this including strval, intval and floatval. There’s a faster way to do each of these.

// this is slower
if(intval($age) > 13)

// this is faster
if((int)$age) > 13)

More information about casting variables here.

Don’t be pushy with arrays
An easy way to append something to an array is to use array_push. There’s a slightly faster way to do this which doesn’t require a function call and doesn’t include a return value.

// this is slower
array_push($myArray, 'myValue);

// this is faster
$myArray[] = ‘myValue’;

Opening and reading files
PHP5 introduced the file_*_contents functions. Not only do these require less lines of code but they also handle all of the core logic internally as a single native PHP function. Traditionally, you would use fopen/fgets/fclose to do this using some sort of loop and incurring numerous function calls.

// this is slower
$fp = fopen('/path/to/file.txt','r');
while(!feof($fp))

// this is faster
file_get_contents('/path/to/file.txt');

Update: As Amit posted in the comments using get_file_contents is a bad idea for large files. Consider using the fopen/fgets/fclose method or readfile.

Strings as an array
A really handy feature of PHP strings is that you can treat it as an array of characters. This is faster than using substr. The two are not identical but can be interchanged for numerous scenarios.

// this is slower
substr($string, 3, 1);

// this is faster
$string[3]

Update: Kevin noted in the comments that using {}s are deprecated in PHP 6 and you can use []s instead.

Being single isn’t so bad
When defining a string PHP lets you use either double or single quotes. The primary difference is that PHP extrapolates variables from inside of double quotes. This means that if you don’t have variables inside your string then single quotes incurs a little less overhead. If you do have variables to inject into a string you can use concatenation or pass pieces to echo as parameters.

// this is slower
echo "Hello, my name is $name";

// this is faster
echo 'Hello, my name is ' . $name;

// this is fastest (using comma instead of period)
echo 'Hello, my name is ' , $name;

Using MySQL
You can use the mysqli extension which provides a faster interface to MySQL. It’s good to note that PHP5 introduced the PDO library which can be used as a wrapper to mysqli. This is slower than using mysqli directly but the benefits of using PDO should be considered.

// this is slower
mysql_query('SELECT id FROM table');

// this is faster
$mysqli->query('SELECT id FROM table');

Storing session in memory
If you use PHP’s native sessions then it’s an easy change to switch from the slower file based session storage to storing sessions in memcache. You’ll need to set a few php.ini configurations including session.save_handler and session.save_path. Of course you’ll need to have a running instance of memcache. No additional changes need to be made in your code.
Checking the beginning of a string
If you need to check the first 5 characters of a string then a regular expression could do the trick. But of course there’s another faster way to do it using strncmp. The benefit is that it doesn’t require using the regular expression engine - an expensive cost for such simple checks.

// this is slower
preg_match('/^abcde/', $string);

// this is faster
strncmp('abcde', $string);

Put the most likely first
When writing conditional statements which have multiple expressions it’s a good idea to always place the most likely expression first. This will vary on whether you’re using || or &&.

// this is slower
if(false || true)

// this is faster
if(true || false)

The first shall be fast
When incrementing a numeric variable it’s common to use the post-increment operator by doing $var++. If possible you can use the faster pre-increment operator by doing ++$var. It’s important to know the difference so you can write your code accordingly.

Conclusion
These are just a few tips and while none of them alone will make your PHP applications blazing fast they don’t hurt. It’s a good habit to write good code from the start since it doesn’t cost any extra time. By all means don’t go back and rewrite existing code to implement minor performance tweaks.

Resources

• http://talks.php.net/show/perf_tunning/
• http://bitfilm.net/2007/08/24/tips-for-faster-php-scripts/
• http://blog.rightbrainnetworks.com/2006/09/18/10-things-you-probably-didnt-know-about-php/
• http://conductr.com/2008/3/3/php-string-manipulation-performance-benchmarking
• http://php.net/manual/

As always…comments welcome!

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