回答編集履歴
2
コードを追加しました。
answer
CHANGED
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@@ -28,4 +28,5 @@
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28
28
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for (int i = 0; i < 4; ++i) {
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29
29
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std::cout << "operator " << ops_str[i] << ": " << half << " " << ops_str[i] << " " << sixth << " = " << ops[i]( half, sixth ) << "\n";
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30
30
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}
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31
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+
}
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31
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-
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32
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+
```
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1
コードを追加しました。
answer
CHANGED
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@@ -2,4 +2,30 @@
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2
2
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3
3
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friend関数を前方宣言すれば良いようです。
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4
4
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https://wandbox.org/permlink/ARajJldEjsVlk1kA
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5
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+
```C++
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6
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+
class Fraction;
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7
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Fraction operator+( Fraction, Fraction );
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8
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Fraction operator-( Fraction, Fraction );
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9
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Fraction operator*( Fraction, Fraction );
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10
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Fraction operator/( Fraction, Fraction );
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11
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+
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12
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class Fraction {
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13
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...
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14
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};
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15
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+
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16
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int main() {
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17
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Fraction half(5, 10);
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5
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-
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18
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+
Fraction sixth(6, 36);
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19
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+
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20
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std::cout << "operator +: " << half << " + " << sixth << " = " << half + sixth << "\n";
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21
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std::cout << "operator -: " << half << " - " << sixth << " = " << half - sixth << "\n";
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22
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std::cout << "operator *: " << half << " * " << sixth << " = " << half * sixth << "\n";
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23
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std::cout << "operator /: " << half << " / " << sixth << " = " << half / sixth << "\n";
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24
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+
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25
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// 以下の正しいやり方が知りたい
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26
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std::vector<std::string> ops_str{"+", "-", "*", "/"};
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27
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std::vector ops{&operator+, &operator-, &operator*, &operator/};
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28
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for (int i = 0; i < 4; ++i) {
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29
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std::cout << "operator " << ops_str[i] << ": " << half << " " << ops_str[i] << " " << sixth << " = " << ops[i]( half, sixth ) << "\n";
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30
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+
}
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31
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}```
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