[英]C++ - Weird code output
此代碼:
class A {
public:
int _a;
A():_a(0) { cout << "A default - ctor, ";}
A(int i):_a(i) { cout << "A int - ctor, ";}
operator int() { cout << "A int - operator, "; return 33;}
virtual ~A() { cout << "A dtor, ";}
};
int main() {
A* a = new A(99);
cout << *a << endl;
return 0;
}
我希望輸出是:一個 int-operator, A int-ctor, 33
但真正的輸出是: A int-ctor, A int-operator, 33
首先你調用"new A(99)"
,它調用"A(int i)"
,它打印"A int - ctor, "
。
以下行調用"cout << *a"
,它調用"operator int()"
,它打印"A int - operator, "
。
然后該行以"cout << [result] << endl"
,它打印結果 (33) 和換行符。
所以"A int - ctor, "
+ "A int - operator, "
+ "33"
+ "endl"
是"A int - ctor, A int - operator, 33"
。
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