Cacti – PHP Specific Constructs

# PHP Specific Constructs

## Traversing Arrays

Use the `foreach ($array as $name => $value)` syntax instead of `while (list($name, $value) = each($array))` syntax when traversing arrays. The former has been demonstrated to be more efficient and does not increment the internal pointer of the array. The `foreach` construct will error if the array is empty or is not an array, so you must check this first.

    if ((is_array($array)) && (sizeof($array) > 0)) {
        foreach ($array as $name => $value) {
            // code
        }
    }

It should be noted that with PHP 7.2 use of `list() = each()` syntax will result in warnings and/or errors. It should also be noted that 7.2 also introduced the need for the variable to implement ICountable which are arrays and objects. You should therefore check if `variable !=== false` before using `sizeof()` or `count()`

## Error Return Values

When an a function needs to return a generic error, it is best to return boolean `false` in PHP. This makes it very straightforward to check for.

    if (file_list() === false) {
        // there was an error
    }

## Regular Expressions Are Slow

Only use PHP's regular expression parsing functions (`preg_match`, `preg_replace`, `preg_quote`, etc) when absolutely needed. Often simpler functions such as `strstr()`, `str_replace()`, `substr()`, and `explode()` can be used, and are much faster.

    $items = explode(':', $string));

It's much quicker than:

    $items = split(':', $string));

## Use `preg` Functions Instead of `ereg`

The POSIX based regular expressions in PHP tend to be slower than their Perl-based equivalents. Use Perl-based regular expression functions unless there is an explicit reason to do otherwise.

NOTE: Do not use any deprecated functions: `eregi_replace`, `ereg`, or `eregi`

## Quotes

Single quotes are used instead of double where possible. Per string, it doesn't really make a huge difference, but when you have thousands upon thousands of them, every little bit helps.

    include_once('./lib/api_tree.php');

However, there isn't any difference between

    "This is a $test"

and

    'This is a ' . $test

Don't bother trying to break out variables out of the string if you are just going to have to concatenate them.

## Including other PHP files

When including other PHP files, you should use the `$config['base_path']` to ensure that the base path is configured properly.

If the main file is a web-based page, it should include `include/auth.php` to ensure that the current user is authenticated.

If the main file is a CLI-based program to be run by end users, it should include `lib/cli_check.php` and support `-h` and `-v` parameters which run `display_help()` and `display_version()` respectively.

    include($config['base_path'] . '/lib/database.php');

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