void is a return-only type declaration indicating the function does not return a value, but the function may still terminate. Therefore, it cannot be part of a union type declaration. Available as of PHP 7.1.0.
A return statement with an expression in a
void function is a compile-time error, even if the
return would not be reached during execution.
This includes return null;; use a bare
return; to exit the function early. The
null mentioned below is only the implicit value of
the call.
Зауваження:
Even if a function has a return type of void, it will still return a value. This value is always
null.
(void)
The (void) syntax may be used to explicitly discard the
result of an expression. This is useful to indicate that ignoring a return
value is intentional, especially when calling a function or method marked
with the NoDiscard
attribute.
Unlike other casts, (void) does not convert the value to
another type and does not produce a value. It is a statement and cannot be
used as part of an expression.
Приклад #1 Discarding a return value
<?php
#[\NoDiscard]
function process(): bool {
return true;
}
(void) process(); // Explicitly discard the return value
?>