php foreach with multidimensional array

Question

I\'m developing a php app that uses a database class to query mySQL.

the class is here: http://net.tutsplus.com/tutorials/php/real-world-oop-with-php-and-mysql/

Answer 1

If you need to do string manipulation on array elements, e.g, then using callback function array_walk_recursive (or even array_walk) works well. Both come in handy when dynamically writing SQL statements.

In this usage, I have this array with each element needing an appended comma and newline.

$some_array = [];

data in $some_array
0: "Some string in an array"
1: "Another string in an array"

Per php.net

If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself.

array_walk_recursive($some_array, function (&$value, $key) {
    $value .= ",\n";
});

Result:
"Some string in an array,\n"
"Another string in an array,\n"

Here's the same concept using array_walk to prepend the database table name to the field.

$fields = [];

data in $fields:
0: "FirstName"
1: "LastName"

$tbl = "Employees"

array_walk($fields, 'prefixOnArray', $tbl.".");

function prefixOnArray(&$value, $key, $prefix) { 
    $value = $prefix.$value; 
}

Result:
"Employees.FirstName"
"Employees.LastName"

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I would be curious to know if performance is at issue over foreach, but for an array with a handful of elements, IMHO, it's hardly worth considering.