在类内部或外部重载运算符有什么区别？
在C ++中，我知道有两种重载方式。 我们可以在内部（如类a ）或外部（如类b ）重载它。 但问题是，这两者在编译时或运行时是否有区别？
class a
{
public:
int x;
a operator+(a p) // operator is overloaded inside class
{
a temp;
temp.x = x;
temp.x = p.x;
return temp;
}
};
class b
{
public:
friend b operator+(b, b);
int x;
};
b operator+(b p1, b p2) // operator is overloaded outside class
{
p1.x += p2.x;
return p1;
}
成员operator+要求LHS成为a - 免费运营商要求LHS或RHS是b而另一方可以转换为b
struct Foo {
Foo() {}
Foo(int) {}
Foo operator+(Foo const & R) { return Foo(); }
};
struct Bar {
Bar() {}
Bar(int) {}
};
Bar operator+(Bar const & L, Bar const & R) {
return Bar();
}
int main() {
Foo f;
f+1; // Will work - the int converts to Foo
1+f; // Won't work - no matching operator
Bar b;
b+1; // Will work - the int converts to Bar
1+b; // Will work, the int converts to a Bar for use in operator+
}
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