在$ _POST中用NULL替换空值

Question

I'm trying to replace empty field values with NULL, but can't seem to figure out how to do it. I've tried array_map, array_filter, and array_walk, but to no avail. Example:

function replaceWithNull($var)
{
    if (empty($var) || $var == ' ') {
        $var = "NULL";
    }
}

array_walk($_POST, "replaceWithNull");

Instead, it remains empty/blank. What am I missing?

Answer 1

You have to use references for argument passing in order to alter the elements in the array:

function replaceWithNull(&$var)
{
    ...
}

Otherwise you will be changing only a copy of the variable.

Read about it here: http://www.php.net/manual/en/functions.arguments.php