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文章目录
- 1,原始代码
- 2,运行没问题，但编译会有警告：elaborated-type-specifier for a scoped enum must not use the ‘class’ keyword
- 3,修改
1,原始代码
#include <iostream>enum class TreeType : int {PINE = 1,CYPRESS = 2,WILLOW = 3
};
std::ostream &operator<<(std::ostream &os, const enum class TreeType &rhs) {switch(rhs) {case TreeType::PINE:os << "PINE"; break;case TreeType::CYPRESS:os << "CYPRESS"; break;case TreeType::WILLOW:os << "WILLOW"; break;}return os;
};int main() {TreeType tree_type;tree_type = TreeType::WILLOW;std::cout << tree_type << std::endl;return 0;
}
2,运行没问题，但编译会有警告：elaborated-type-specifier for a scoped enum must not use the ‘class’ keyword
3,修改
#include <iostream>enum class TreeType : int {PINE = 1,CYPRESS = 2,WILLOW = 3
};
//std::ostream &operator<<(std::ostream &os, const enum class TreeType &rhs) {
// 改为
std::ostream &operator<<(std::ostream &os, const enum TreeType &rhs) {switch(rhs) {case TreeType::PINE:os << "PINE"; break;case TreeType::CYPRESS:os << "CYPRESS"; break;case TreeType::WILLOW:os << "WILLOW"; break;}return os;
};int main() {TreeType tree_type;tree_type = TreeType::WILLOW;std::cout << tree_type << std::endl;return 0;
}
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