Allegro中的平等运算符重载 [英] Equality Operator Overloading in Allegro

问题描述

我的一个朋友正在尝试重载用于在Allegro中比较颜色的相等运算符，但是它不起作用.他得到错误操作符不匹配==".这是在Color类/结构之外重载的，重载了操作员功能如下所示:

One of my friends is trying to overload an equality operator for comparing colours in Allegro, however it does not work,He gets the error "no match for operator==" This is overloaded outside the Color class/struct, the overloaded operator function is shown below:

typedef ALLEGRO_COLOR Color;
bool operator==(const Color& rhs) const
{
 if(_col.a==rhs.a && _col.b==rhs.b && _col.g==rhs.g && _col.r==rhs.r)
 return true;
 else
 return false;
}
.
.
.
//Data member
Color _col

我认为这是行不通的，因为已定义了运算符&在Allegro的ALLEGRO_COLOR外部实现，对吗?如何解决这个问题，是否有可能在Allegro Color结构之外重载.

Im thinking this does not work because the operator is defined & implemented outside the ALLEGRO_COLOR in Allegro,right? How can this problem be solved, is it possible to overload outside the Allegro Color struct.

推荐答案

operator==是二进制运算符，但是只有一个参数.试试这个:

operator== is a binary operator, but you only have one parameter. Try this:

bool operator==(const Color& _col, const Color& rhs) { ... }

---

后记:此表单的代码:

---

Postscript: code of this form:

if ( condition )
    return true;
else
    return false;

在C ++中是不必要的冗长.最好这样做:

is needlessly verbose in C++. Better to do this:

return condition;

在您的情况下，我希望查看:

In your case, I'd prefer to see:

return _col.a==rhs.a && _col.b==rhs.b && _col.g==rhs.g && _col.r==rhs.r;

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