You can; the null pointer is implicitly converted into boolean false while non-null pointers are converted into true. From the C++11 standard, section on Boolean Conversions:
A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a
prvalue of type
bool. A zero value, null pointer value, or null member pointer value is converted to
false;
any other value is converted to
true
. A prvalue of type
std::nullptr_t
can be converted to a prvalue of
type
bool
; the resulting value is
false
.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
