[英]operator+ overload left and right
我想重載operator +在兩側工作。當我使用operator +時,我想將元素推入類的向量中。這是我的代碼:
template<typename TElement>
class grades {
private:
vector<TElement> v;
public:
grades& operator+(const int& a) {
v.push_back(a);
return *this;
}
grades& operator=(const grades& g) {
v = g.v;
return *this;
}
friend grades& operator+(const int& a,const grades& g) {
//here i get some errors if i put my code
return *this;
}
};
int main() {
grades<int> myg;
myg = 10 + myg; // this operation i want
myg = myg + 9; //this work
return 0;
}
operator+
表示副本。 operator+=
表示就地突變。
這可能更慣用:
#include <vector>
using namespace std;
template<typename TElement>
class grades {
private:
vector<TElement> v;
public:
grades& operator+=(int a)
{
v.push_back(a);
}
// redundant
// grades& operator=(const grades& g) {
// v = g.v;
// return *this;
// }
friend grades operator+(grades g, const int& a) {
g += a;
return g;
}
friend grades operator+(const int& a,grades g) {
g.v.insert(g.v.begin(), a);
return g;
}
};
int main() {
grades<int> myg;
myg = 10 + myg; // this now works
myg = myg + 9; //this work
return 0;
}
運算符+應該返回副本
template<typename TElement>
class grades {
private:
vector<TElement> v;
public:
grades operator+(const TElement& a) const {
grades ret(*this);
ret.v.push_back(a);
return ret;
}
friend grades operator+(const TElement& a,const grades& g) {
return g+a;
}
};
int main() {
grades<int> myg;
myg = 10 + myg; // this operation i want
myg = myg + 9; //this work
return 0;
}
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