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19. Type Declarations

Strengthening function contracts.

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PHP allows scalar and class type hints on parameters and return types, e.g. function add(int $a, int $b): int. Declaring `declare(strict_types=1);` at the top of a file enforces strict type checking instead of coercion.

Nullable types are written with a leading question mark, such as ?string, allowing null in addition to the declared type.

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