Type Juggling & Casting

PHP automatically converts ("juggles") types in many operations — convenient, but a frequent source of subtle bugs if you're not watching for it.

$total = "5" + 3;      // 8 — the string "5" is juggled to an int
$label = "Total: " . 5; // "Total: 5" — . concatenates, converting 5 to a string

$count = (int) "42abc"; // 42 — casts up to the first non-numeric character
$flag = (bool) "";       // false — empty string is "falsy"

Common mistakes

• Using == (loose comparison), which juggles types before comparing: 0 == "abc" was true in PHP before 8.0. Prefer === (covered next, in Operators) to avoid this entirely.