[RESOLVED] Recursive function return value

[vertmonkee]

I am building a recursive function that traverses a hierarchy in the database until it can not find a parent element.

An example of what can be found in the database is

codeID, codeDescription
1, AB
2, AB.CD
3, AB.CD.EF
4, AB.CD.EF.GH

I start with the codeDescription of AB.CD.EF.GH which is assigned to the $my_string variable.

The following is my code.

function reduceString($string, $information_array = array()) {

//Set up an array to hold the values
$habitat_array = $information_array;

print_r($habitat_array);

echo "<br />";

//Find the last occurence of a period (.) in the string
$position = strrpos($string, ".");

//Remove the end of the string to the final period (.)
$end_string = substr($string, 0, $position);

//Run a query to see if there is a parent element
$new_sql = "SELECT * FROM `codes` WHERE `codeDescription` = '$end_string';";

$new_result = mysql_query($new_sql) or die(mysql_error());

//Check if we have any results
if(mysql_num_rows($new_result) != 0) {

	$habitat = mysql_fetch_assoc($new_result);

	$habitat_array[$habitat['codeID']] = $habitat['codeDescription'];

	//Call the function again
	reduceString($end_string, $habitat_array);

} else {

	$return_array = $habitat_array;

	echo "<p>Return array<br />";
	print_r($return_array);
	echo "</p>";

}

return(isset($return_array) ? $return_array : false);

}

$my_new_array = reduceString($my_string);

echo "<p>My array from the function</p>";

print_r($my_new_array);

The final line where i print out the contents of $my_new_array comes up blank even though on the final loop through the array is printed out at the beginning containing exactly what I need.

Can anyone point out what I am doing wrong?

Thanks for any help.

[vertmonkee]

Found the solution today.

The new code has one simple addition to it.

function reduceString($string, $information_array = array()) {

//Set up an array to hold the values
$habitat_array = $information_array;

print_r($habitat_array);

echo "<br />";

//Find the last occurence of a period (.) in the string
$position = strrpos($string, ".");

//Remove the end of the string to the final period (.)
$end_string = substr($string, 0, $position);

//Run a query to see if there is a parent element
$new_sql = "SELECT * FROM `codes` WHERE `codeDescription` = '$end_string';";

$new_result = mysql_query($new_sql) or die(mysql_error());

//Check if we have any results
if(mysql_num_rows($new_result) != 0) {

    $habitat = mysql_fetch_assoc($new_result);

    $habitat_array[$habitat['codeID']] = $habitat['codeDescription'];

    //Call the function again
    return reduceString($end_string, $habitat_array);

} else {

    $return_array = $habitat_array;

    echo "<p>Return array<br />";
    print_r($return_array);
    echo "</p>";

}

return(isset($return_array) ? $return_array : false);

}

$my_new_array = reduceString($my_string);

echo "<p>My array from the function</p>";

print_r($my_new_array); 

On line 29 I needed to add a return before calling the function again.

[emygdio]

vertmonkee;10895364 wrote:

Found the solution today.

The new code has one simple addition to it.

function reduceString($string, $information_array = array()) {

//Set up an array to hold the values
$habitat_array = $information_array;

print_r($habitat_array);

echo "<br />";

//Find the last occurence of a period (.) in the string
$position = strrpos($string, ".");

//Remove the end of the string to the final period (.)
$end_string = substr($string, 0, $position);

//Run a query to see if there is a parent element
$new_sql = "SELECT * FROM `codes` WHERE `codeDescription` = '$end_string';";

$new_result = mysql_query($new_sql) or die(mysql_error());

//Check if we have any results
if(mysql_num_rows($new_result) != 0) {

    $habitat = mysql_fetch_assoc($new_result);

    $habitat_array[$habitat['codeID']] = $habitat['codeDescription'];

    //Call the function again
    return reduceString($end_string, $habitat_array);

} else {

    $return_array = $habitat_array;

    echo "<p>Return array<br />";
    print_r($return_array);
    echo "</p>";

}

return(isset($return_array) ? $return_array : false);

}

$my_new_array = reduceString($my_string);

echo "<p>My array from the function</p>";

print_r($my_new_array); 

On line 29 I needed to add a return before calling the function again.

I had the same problem, and when I added the first return into my "if", the function returned the appropriate value. Is this some kind of problem in the scope variable of the recursive function?

[NogDog]

emygdio;11042267 wrote:

I had the same problem, and when I added the first return into my "if", the function returned the appropriate value. Is this some kind of problem in the scope variable of the recursive function?

At a quick glance, I suspect instead of a return at that point, it could just have assigned the result of the recursive call to $return_array, then let the final return statement do its thing. (But I've not tested it to make sure.)