Question

I am processing a CSV authored by a remote system. I don’t want to assume they won’t change what fields they provide or their order so I am parsing a header row for the indices in the CSV of fields and mapping these into an array I can use for lookups and updates.

Thing is the way I am doing it tests false for index zero:

foreach ($field_map_array as $local_field => $silverpop_field) {
    if ($idx = array_search($silverpop_field, $fields)) {
        $local_to_sp[$local_table][$local_field] = $idx;
    } // index found
}

What’s a better way to do that?

Answer 1

array_search returns an integer if it finds the needle, and FALSE otherwise, so test it explicitly using the !== / not identical operator:

foreach ($field_map_array as $local_field => $silverpop_field) {
    if (($idx = array_search($silverpop_field, $fields)) !== FALSE) {
        $local_to_sp[$local_table][$local_field] = $idx;
    } // index found
}

Here’s how the manual describes the difference between != (not equal) and !== (not identical) (emphasis added):

$a != $b Not equal TRUE if $a is not equal to $b after type juggling.

$a !== $b Not identical TRUE if $a is not equal to $b, or they are not of the same type.

The problem with your code is that if(0) is interpreted as if(0 != FALSE). Type juggling lets it cast FALSE to the integer 0, and 0 != 0 is obviously false. With !== type juggling doesn’t occur, so 0 !== FALSE is true (since they’re not the same type).

I’d recommend using === and !== whenever possible, since they are more predictable, and predictable code tends to be less buggy and easier to work with.