Question

How to check if integer addition will overflow in PHP

Answer 1

function addingWillOverflow(int $x, int $y): bool {
    return (($x > 0) && ($y > PHP_INT_MAX - $x)) || (($x < 0) && ($y < PHP_INT_MIN - $x));
}

$x = 39839299;
$y = 1472783642;
echo addingWillOverflow($x, $y) ? "true" : "false", PHP_EOL;

$x = 9223372036854775807; // PHP_INT_MAX
$y = 1872783642;
echo addingWillOverflow($x, $y) ? "true" : "false", PHP_EOL;


/*
run:

false
true

*/

 

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