Variable Operators in PHP

Question

Given this example, how would I return the result of the equation rather than the equation itself as a string?

$operator = \'+\';
foreach($resultSet as $item         


        

Answer 1

To achieve exactly that, you can use create_function

$operator = '+';
$func = create_function('$a,$b', "return \$a $operator \$b;");
foreach($resultSet as $item){
    $result = $func($item, 1);
    echo $result;
}

A cleaner solution is possible with lambdas (php5.3 required)

$func = function($a, $b) { return $a + $b; };
foreach($resultSet as $item){
    $result = $func($item, 1);
    echo $result;
}

See also array_sum, array_reduce

Advanced example with array_reduce and lambdas

$ary = array(
    array('foo' => 1, 'bar' => 91),
    array('foo' => 2, 'bar' => 92),
    array('foo' => 3, 'bar' => 93),
    array('foo' => 4, 'bar' => 94),
    array('foo' => 5, 'bar' => 95),
);

$sumOfFoos = array_reduce($ary, 
    function($val, $item) { return $val + $item['foo']; } 
);
$sumOfBars = array_reduce($ary, 
    function($val, $item) { return $val + $item['bar']; } 
);

The main point is, that instead of 'variable operators' (which is not possible in php), you should rather use variable functions (which is possible and much more flexible).