Convert PHP class' constant into string - php

Question

I have a class with constants like this:
class AClass
{
const CODE_NAME_123 = "value1";
const CODE_NAME_456 = "value2";
}
Is there a way to convert the name of a constant like AClass::CODE_NAME_123 into a string in order to, e.g., extract the trailing digits from the string?

Answer 1

You can use something like this:
//PHP's ReflectionClass will allow us to get the details of a particular class
$r = new ReflectionClass('AClass');
$constants = $r->getConstants();
//all constants are now stored in an array called $constants
var_dump($constants);
//example showing how to get trailing digits from constant names
$digits = array();
foreach($constants as $constantName => $constantValue){
$exploded = explode("_", $constantName);
$digits[] = $exploded[2];
}
var_dump($digits);

Answer 2

You can use ReflectionClass::getConstants() and iterate through the result to find a constant with a specific value, and then get the last digits from the constant name with regex:
<?php
class AClass
{
const CODE_NAME_123 = "foo";
const CODE_NAME_456 = "bar";
}
function findConstantWithValue($class, $searchValue) {
$reflectionClass = new ReflectionClass($class);
foreach ($reflectionClass->getConstants() as $constant => $value) {
if ($value === $searchValue) {
return $constant;
}
}
return null;
}
function findConstantDigitsWithValue($class, $searchValue) {
$constant = findConstantWithValue($class, $searchValue);
if ($constant !== null && preg_match('/\d+$/', $constant, $matches)) {
return $matches[0];
}
return null;
}
var_dump( findConstantDigitsWithValue('AClass', 'foo') ); //string(3) "123"
var_dump( findConstantDigitsWithValue('AClass', 'bar') ); //string(3) "456"
var_dump( findConstantDigitsWithValue('AClass', 'nop') ); //NULL
?>
DEMO

Answer 3

Use ReflectionClass() and loop through the resulting keys applying a preg_match to each value to extract the last 3 numbers of the string:
class AClass
{
const CODE_NAME_123 = "";
const CODE_NAME_456 = "";
}
$constants = new ReflectionClass('AClass');
$constants_array = $constants->getConstants();
foreach ($constants_array as $constant_key => $constant_value) {
preg_match('/\d{3}$/i', $constant_key, $matches);
echo '<pre>';
print_r($matches);
echo '</pre>';
}
The output would be:
Array
(
[0] => 123
)
Array
(
[0] => 456
)