1.PNG
    2.PNG

    1. #include <bits/stdc++.h>
    2. using namespace std;
    4. //Dividing Line---------------------------------------------------------------------------------------------
    5. class demo
    6. {
    7.     public:
    8.         int n;
    9.         demo(int i = 0) : n(i){};
    10.         demo &operator++(void); //前置
    11.         demo operator++(int x); //后置
    12.         friend demo &operator--(demo &);
    13.         friend demo operator--(demo &, int);
    14. };
    16. demo &demo::operator++(void)
    17. {
    18.     ++n;
    19.     return *this;
    20. }
    22. demo demo::operator++(int x)
    23. {
    24.     demo tmp(*this);
    25.     n++;
    26.     return tmp;
    27. }
    29. demo &operator--(demo &c)
    30. {
    31.     --c.n;
    32.     return c;
    33. }
    35. demo operator--(demo &c, int useless)
    36. {
    37.     demo tmp(c);
    38.     c.n--;
    39.     return tmp;
    40. }
    42. ostream &operator<<(ostream &os, const demo &c)
    43. {
    44.     os << c.n;
    45.     return os;
    46. }
    47. //Dividing Line-----------------------------------------------------------------------------------------------
    49. int main(void)
    50. {
    51.     demo d(8);
    52.     cout << d++ << endl;
    53.     cout << d << endl;
    54.     cout << ++d << endl;
    55.     cout << d << endl;
    56.     cout << d-- << endl;
    57.     cout << d << endl;
    58.     cout << --d << endl;
    59.     cout << d << endl;
    60.     return 0;
    61. }
    63. /*
    64. 8
    65. 9
    66. 10
    67. 10
    68. 10
    69. 9
    70. 8
    71. 8
    72. */