Question

我试图增加枚举类型，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，我收到错误：

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？什么是正确的方法或增加枚举类型的更好方法？

Answer 1

似乎您的operator ++从多个编译单元导出。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）。可以使用以下选项来解决问题：

将operator ++保留在头文件中，但将其声明为inline
仅在头文件中保留声明并将定义移动到.cpp文件

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

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;
}

架构x86_64的C ++重复符号...增加枚举类型

1 个答案: