c++ - 架构x86_64的C++重复符号..递增枚举类型

我试图增加一个枚举类型，所以我以这种方式重载了运算符++:

 enum QuarterType{
            FIRST_QUARTER,
            SECOND_QUARTER,
            THIRD_QUARTER,
            FOURTH_QUARTER
        };

重载Operator ++:

QuarterType& operator++(QuarterType& quarter){
    switch (quarter) {
        case FIRST_QUARTER:
            return quarter= SECOND_QUARTER;
        case SECOND_QUARTER:
            return quarter=THIRD_QUARTER;
        case THIRD_QUARTER:
            return quarter=FOURTH_QUARTER;
        case FOURTH_QUARTER:
            return quarter=FIRST_QUARTER;
    }
}

但是当我编译项目时，我得到了错误:

duplicate symbol __ZN3mtmppERNS_11QuarterTypeE in:
    /Users/../Library/Developer/Xcode/DerivedData/mtm-crtygivbbxwmodgeasndvnjnpczt/Build/Intermediates/mtm.build/Debug/mtm.build/Objects-normal/x86_64/SecurityExample.o
    /Users/../Library/Developer/Xcode/DerivedData/mtm-crtygivbbxwmodgeasndvnjnpczt/Build/Intermediates/mtm.build/Debug/mtm.build/Objects-normal/x86_64/Quarters.o
duplicate symbol __ZN3mtmppERNS_11QuarterTypeE in:
    /Users/../Library/Developer/Xcode/DerivedData/mtm-crtygivbbxwmodgeasndvnjnpczt/Build/Intermediates/mtm.build/Debug/mtm.build/Objects-normal/x86_64/SecurityExample.o
    /Users/../Library/Developer/Xcode/DerivedData/mtm-crtygivbbxwmodgeasndvnjnpczt/Build/Intermediates/mtm.build/Debug/mtm.build/Objects-normal/x86_64/Security.o
ld: 2 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我该如何解决？什么是增加枚举类型的正确方法或更好的方法？

最佳答案

看来您的operator ++已从多个编译单元中导出。这可能导致重复的符号错误，其原因可能是头文件中operator ++的定义(不仅仅是声明)。以下选项可用于解决问题:

将operator ++保留在头文件中，但将其声明为inline

仅将声明保留在头文件中，并将定义移至.cpp文件中。

回答第二个问题(关于增加枚举类型的更好方法)，我认为这是C++ 11中的以下内容(clang编译器的-std = c++ 11选项):

enum class QuarterType : int {
    FIRST_QUARTER = 0,
    SECOND_QUARTER = 1,
    THIRD_QUARTER = 2,
    FOURTH_QUARTER = 3,
    TOTAL_QUARTERS = 4
};
inline QuarterType& operator++(QuarterType& quarter) {
    int currentQuarter = static_cast<int>(quarter);
    int nextQuarter = (currentQuarter+1)
        % static_cast<int>(QuarterType::TOTAL_QUARTERS);
    quarter = static_cast<QuarterType>(nextQuarter);
    return quarter;
}

关于c++ - 架构x86_64的C++重复符号..递增枚举类型，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/31132747/