推 hyujr:是因為還沒有真正搞懂C++的語法.. 03/06 00:33
→ hyujr:真是太感謝這麼詳細圖解！ 03/06 00:34
內部變數的資料儲存變化大概如下
b1(1,2) Base Base::computer Base
value1 = 1 ===> value1 = 4
value2 = 2 value2 = 6
--------------------------------------------------------------
d1(2,3,4) Base Base
value1 = 2 value1 = 7
value2 = 3 Base::computer value2 = 15
===>
Derived Derived
value2 = 5 value2 = 5
value3 = 4 value3 = 4
--------------------------------------------------------------
d2(3,4,5) Base Base
value1 = 3 value1 = 3
value2 = 4 None value2 = 4
===>
Derived Derived
value2 = 7 value2 = 7
value3 = 5 value3 = 5
--------------------------------------------------------------
d3(4,5,6) Base Base
value1 = 4 value1 = 3
value2 = 5 value2 = 5
Virtual Derived::calculate
Derived ===> Derived
value2 = 9 value2 = 6
value3 = 6 value3 = 4
---------------------------------------------------------------
d4(5,6,7) Base Base
value1 = 5 value1 = 7
value2 = 6 value2 = 12
Base::compute
Derived ===> Derived
value2 = 11 value2 = 11
value3 = 7 value3 = 7
Base
value1 = 4
value2 = 12
Virtual Derived::calculate
===> Derived
value2 = 8
value3 = 5
----------------------------------------------------------------
new Derived(6, 7, 8) Base Base
value1 = 6 value1 = 5
value2 = 7 value2 = 7
Base::compute1
Derived Virtual Derived::calculate Derived
value2 = 13 ===> value2 = 10
value3 = 8 value3 = 6
※ 引述《hyujr (鬱)》之銘言：
: 因為本身只學過C語言也沒學得很深
: 突然發現考題裡面有C++有點嚇到
: 不過就硬頭皮把程式碼打下來
: 邊想邊對照Output
: 後來做了幾份大概有些概念
: 雖然也不確定到底思考的流程是不是對的= =
: 但有個地方實在想不通
: 不知道有沒有人可以幫我說明一下..
: # include <string>
: # include <iostream>
: class Base
: {
: public:
: Base(int b1 = 0, int b2 = 0) {value1 = b1; value2 = b2;}
: void compute(int x) {value1 += x; value2 *= x;}
: void compute1(int x) {calculate(x);}
: virtual void calculate(int x) {value1 = x; value2 = x * x;}
: void print() {cout << value1 + value2 << " ";}
: int value1, value2;
: };
: class Derived: public Base
: {
: public:
: Derived(int x1, int x2, int x3):Base(x1, x2)
: {value2 = x1 + x2; value3 = x3;}
: virtual void calculate(int x) {value1 = x; value2 = 2 * x; value3 = x + 1;}
: void print() {cout << value2 + value3 << " ";}
: int value2, value3;
: };
: void main()
: {
: Base b1(1, 2); b1.print();
: b1.compute(3); b1.print();
: Derived d1(2, 3, 4); d1.print();
: d1.compute(5); d1.Base::print();
: Derived d2(3, 4, 5); Base b2; b2 = d2; b2.print();
: Derived d3(4, 5, 6); d3.calculate(3); d3.print();
: d3.Base::print(); //這行
: Derived d4(5, 6, 7); Base *b4; b4 = &d4; b4->compute(2); b4->print();
: b4->calculate(4); d4.print();
: Base *b5 = new Derived(6, 7, 8); b5->compute1(5); b5->print(); //這行
: system("pause");
: }
: 有標記那兩行的所輸出結果想不通
: 有沒有人可以幫我說明一下~
: 謝謝！
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