The get_defined_constants() Function

[iwato]

BACKGROUND: The following code is designed to find all of the pre-defined constants that begin with the same substring. What it is able to achieve is to find only the first constant containing the substring. While attempting to discover a way to remedy this problem I stumbled on the following riddle that I would like you to help me solve.Under normal circumstances a single foreach statement of the following structureforeach ($array as $key => $value) { echo $value;}returns only the key-name of the nested subarray and the value array.In contrast, following code returns the full key-value pairs for all elements of both the array and subarrays generated by the get_defined_constants() function.foreach (get_defined_constants() as $key => $value) { echo $key . ': ' . $value . '<br />';}Can you explain the above contradiction?

<?php	function returnConstants($prefix) {		foreach (get_defined_constants() as $key=>$value) {			if (substr($key,0,strlen($prefix))==$prefix) {				$dump[$key] = $value;				if(empty($dump)) {					return "Error: No Constants found with prefix '". $prefix . "'";				} else {					return $dump;				}			}		}	}?>

Roddy

[justsomeguy]

I don't understand what you think the contradiction is. Both loops do the same thing, they loop over an array and set $key and $value to the keys and values in the array.The function you posted stops after the first one because the return statement is inside the loop instead of outside.

[iwato]

I don't understand what you think the contradiction is. Both loops do the same thing, they loop over an array and set $key and $value to the keys and values in the array.

The contradiction is that the second loop does what the following should do:

foreach (get_defined_constants() as $key => $value) {	foreach($value as $constant name => $constant_value)		 echo $constant_name . ': ' . $constant_value . '<br />';	}}

Once again, in order to get at the value of an element of a subarray an additional foreach loop is required. This is not so when the array is the one generated by the get_defined_constants() function.Roddy

[boen_robot]

My tests confirm otherwise, i.e. what the manual suggests: By default, the array returned by get_defined_constants() is one dimensional, so a single foreach loop should echo all constants and their values.If you supply the parameter to true, it should return a two dimensional array instead... this is testing on PHP 5.3.2 VC6 Thread Safe, Windows... if without the parameter you get the two dimensional version, you've found a bug on PHP's MAC version.

[iwato]

My tests confirm otherwise, i.e. what the manual suggests: By default, the array returned by get_defined_constants() is one dimensional, so a single foreach loop should echo all constants and their values.If you supply the parameter to true, it should return a two dimensional array instead... this is testing on PHP 5.3.2 VC6 Thread Safe, Windows... if without the parameter you get the two dimensional version, you've found a bug on PHP's MAC version.

We read the same passage, but a phpversion() function call informed me that my version of PHP is 5.2.6. I have now performed the following two experiments and obtained the results indicated:

<h3>The key-value Pairs Generated by a foreach-Statement with $categorize Set to True</h3>	<?php		foreach (get_defined_constants(true) as $key => $value) {			echo $key . ': ' . $value . '<br />';		}	?>

Result: A list of subarrays with their names listed as keys and their values as array. No constants and no constant values appeared.

<h3>The key-value Pairs Generated by a foreach-Statement with $categorize Not Set</h3>	<?php		foreach (get_defined_constants() as $key => $value) {			echo $key . ': ' . $value . '<br />';		}	?>

Result: A very long uninterrupted list of constants and their respective value.In short, no difference between PHP Version 5.2.6 (on Mac) and 5.3.2 (on Windows).As always, many thanks.Now, I have only to take justsomeguys suggestion and fix the way my loop functions.Have a great day!Roddy