回答編集履歴
1
追記
answer
CHANGED
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@@ -42,4 +42,48 @@
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42
42
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2+3= 6
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43
43
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last result = 6
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44
44
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*/
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45
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+
```
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46
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+
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47
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[追記] こゆこと?
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48
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+
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49
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```C++
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50
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#include <iostream>
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51
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+
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52
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class Operation {
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53
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int last_;
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54
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public:
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55
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int add(int x, int y) { return last_ = x+y; }
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56
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int sub(int x, int y) { return last_ = x-y; }
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57
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int mul(int x, int y) { return last_ = x*y; }
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58
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int last() const { return last_; }
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59
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};
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60
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61
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class Foo {
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62
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Operation* opr_;
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63
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public:
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64
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void set(Operation* opr) {
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65
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opr_ = opr;
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66
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}
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67
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int exec_add(int x, int y) {
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68
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return opr_->add(x, y);
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69
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}
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70
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};
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71
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72
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int main() {
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73
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using namespace std;
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74
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75
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Operation op;
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76
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Foo foo;
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77
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78
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foo.set(&op);
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79
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cout << "1+2= " << foo.exec_add(1,2) << endl;
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80
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cout << "2+3= " << foo.exec_add(2,3) << endl;
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81
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cout << "last result = " << op.last() << endl;
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82
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}
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83
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84
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/* 実行結果
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85
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1+2= 3
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86
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2+3= 5
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87
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last result = 5
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88
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*/
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45
89
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```
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