我如何定义一个以 struct 为键的 QMap

Question

我尝试定义一个 QMap，它的关键是一个 C++ 结构。

struct ProcInfo_S
{
    quint8 tech = 0;
    quint8 direction = 0;
    quint8 category = 0;
};

QMap<ProcInfo_S, uint64_t> G;
G[{2,3,4}] = 2;

但是当我编译这段代码时，出现以下编译错误：

error: no match for ‘operator<’ (operand types are ‘const MainWindow::MainWindow(QWidget*)::ProcInfo_S’

Answer 1

地图中元素的顺序通过调用键的 operator< 来确定。来自 documentation:

[...] The key type of a QMap must provide operator<() specifying a total order. Since Qt 5.8.1 it is also safe to use a pointer type as key, even if the underlying operator<() does not provide a total order.

实现它的一种方法是例如：

struct ProcInfo_S
{
    quint8 tech = 0;
    quint8 direction = 0;
    quint8 category = 0;
    bool operator<( const ProcInfo_S& other) const {
         return std::tie(tech,direction,category) < std::tie(other.tech,other.direction,other.category);
    }
};

我如何定义一个以 struct 为键的 QMap

How I can define a QMap with struct as key

c++

qt

qmap