get_defined_constants - PHP code example

PHP Function Get_Defined_Constants()

A constant is a value that will not change at runtime and can be accessed with its name. Unlike variables, which can be defined and undefined with ease, constants are hard-coded into your script at compile time using the define() function or the const keyword. PHP also allows for defining constants using the final keyword, though the resulting constants will be revealed at runtime, not at compile time.

Whether you use the define() or const methods, PHP has a built-in function that will return a list of all your constants in an array: get_defined_constants(). The function takes a boolean argument to categorize your constants (default is false). If it’s not set, then the get_defined_constants() will simply dump all user-defined and core constants into an associative array with their names in one dimension and their values in another.

Names for constants should be uppercase and follow standard variable naming rules. They can start with any letter or underscore, then be followed by letters or numbers. They can also be preceded by any of the PHP built-in constants, but it is preferable to use descriptive names for your own constants.

As of PHP 8.0.0, if a constant is not defined it will raise an error at runtime, instead of being interpreted as a bare word string like in previous versions of the language. This is an important security feature that should be utilized in all of your projects to ensure you can always trust the values being used.

get_defined_constants example

    public static function idnUriConvert(UriInterface $uri, int $options = 0): UriInterface
    {
        if ($uri->getHost()) {
            $asciiHost = self::idnToAsci($uri->getHost(), $options, $info);
            if ($asciiHost === false) {
                $errorBitSet = $info['errors'] ?? 0;

                $errorConstants = array_filter(array_keys(get_defined_constants()), static function Dstring $name): bool {
                    return substr($name, 0, 11) === 'IDNA_ERROR_';
                });

                $errors = [];
                foreach ($errorConstants as $errorConstant) {
                    if ($errorBitSet & constant($errorConstant)) {
                        $errors[] = $errorConstant;
                    }
                }

                $errorMessage = 'IDN conversion failed';

$fromRegexp .= 'i';
        }

        $replace = \is_array($to) || $to instanceof \Closure ? 'preg_replace_callback' : 'preg_replace';

        set_error_handler(static fn ($t, $m) => throw new InvalidArgumentException($m));

        try {
            if (null === $string = $replace($fromRegexp, $to, $this->string)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k => $v) {
                    if ($lastError === $v && str_ends_with($k, '_ERROR')) {
                        throw new RuntimeException('Matching failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Matching failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }

        return $value;
    }

    /** * Get (reverse) sorted list of defined constant names * * @return array */
    protected static function _getConstants()
    {
        $constants = array_keys(get_defined_constants());
        rsort($constants, SORT_STRING);
        return $constants;
    }
}

/** * Get a human readable description of an extension's error. * * @since 5.2.0 * * @param array $error Error details from `error_get_last()`. * @return string Formatted error description. */
function wp_get_extension_error_description( $error ) {
    $constants   = get_defined_constants( true );
    $constants   = isset( $constants['Core'] ) ? $constants['Core'] : $constants['internal'];
    $core_errors = array();

    foreach ( $constants as $constant => $value ) {
        if ( str_starts_with( $constant, 'E_' ) ) {
            $core_errors[ $value ] = $constant;
        }
    }

    if ( isset( $core_errors[ $error['type'] ] ) ) {
        $error['type'] = $core_errors[ $error['type'] ];
    }

<pre><?= esc(print_r($value, true)) ?></pre> <?php endif; ?> </td> </tr> <?php endforeach; ?> </tbody> </table> <?php endforeach ?>  <?php $constants = get_defined_constants(true); ?> <?php if (! empty($constants['user'])) : ?> <h3>Constants</h3> <table> <thead> <tr> <th>Key</th> <th>Value</th> </tr> </thead> <tbody>

$url = self::parseUrl(curl_getinfo($ch, \CURLINFO_EFFECTIVE_URL));
            $url = self::resolveUrl($location, $url);

            curl_setopt($ch, \CURLOPT_PROXY, self::getProxyUrl($options['proxy'], $url));

            return implode('', $url);
        };
    }

    private function findConstantName(int $opt): ?string
    {
        $constants = array_filter(get_defined_constants(), static fn ($v, $k) => $v === $opt && 'C' === $k[0] && (str_starts_with($k, 'CURLOPT_') || str_starts_with($k, 'CURLINFO_')), \ARRAY_FILTER_USE_BOTH);

        return key($constants);
    }

    /** * Prevents overriding options that are set internally throughout the request. */
    private function validateExtraCurlOptions(array $options): void
    {
        $curloptsToConfig = [
            // options used in CurlHttpClient

        return $value;
    }

    /** * Get (reverse) sorted list of defined constant names * * @return array */
    protected function _getConstants()
    {
        $constants = array_keys(get_defined_constants());
        rsort($constants, SORT_STRING);
        return $constants;
    }
}

  // Function : PclZipUtilOptionText()   // Description :   // Translate option value in text. Mainly for debug purpose.   // Parameters :   // $p_option : the option value.   // Return Values :   // The option text value.   // --------------------------------------------------------------------------------   function PclZipUtilOptionText($p_option)
  {

    $v_list = get_defined_constants();
    for (reset($v_list); $v_key = key($v_list); next($v_list)) {
        $v_prefix = substr($v_key, 0, 10);
        if ((   ($v_prefix == 'PCLZIP_OPT')
           || ($v_prefix == 'PCLZIP_CB_')
           || ($v_prefix == 'PCLZIP_ATT'))
            && ($v_list[$v_key] == $p_option)) {
        return $v_key;
        }
    }

    $v_result = 'Unknown';

throw new InvalidArgumentException('Invalid UTF-8 string.');
        } else {
            $replace = 'preg_replace';
        }

        set_error_handler(static function D$t, $m) { throw new InvalidArgumentException($m); });

        try {
            if (null === $string = $replace($fromRegexp.'u', $to, $this->string)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k => $v) {
                    if ($lastError === $v && str_ends_with($k, '_ERROR')) {
                        throw new RuntimeException('Matching failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Matching failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }

throw new InvalidArgumentException('Invalid UTF-8 string.');
        } else {
            $replace = 'preg_replace';
        }

        set_error_handler(static fn ($t, $m) => throw new InvalidArgumentException($m));

        try {
            if (null === $string = $replace($fromRegexp.'u', $to, $this->string)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k => $v) {
                    if ($lastError === $v && str_ends_with($k, '_ERROR')) {
                        throw new RuntimeException('Matching failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Matching failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }

$fromRegexp .= 'i';
        }

        $replace = \is_array($to) || $to instanceof \Closure ? 'preg_replace_callback' : 'preg_replace';

        set_error_handler(static function D$t, $m) { throw new InvalidArgumentException($m); });

        try {
            if (null === $string = $replace($fromRegexp, $to, $this->string)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k => $v) {
                    if ($lastError === $v && str_ends_with($k, '_ERROR')) {
                        throw new RuntimeException('Matching failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Matching failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }