正确尝试/捕获无序映射异常

Question

我有这个：

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// static enum of supported HttpRequest to match requestToString\nstatic const enum HttpRequest {\n    GET, \n    POST,\n    PUT,\n    DELETE,\n    OPTIONS,\n    HEAD,\n    TRACE\n};\n\n// typedef for the HttpRequests Map\ntypedef boost::unordered_map<enum HttpRequest, const char*> HttpRequests;\n\n// define the HttpRequest Map to get static list of supported requests\nstatic const HttpRequests requestToString = map_list_of\n    (GET,    "GET")\n    (POST,   "POST")\n    (PUT,    "PUT")\n    (DELETE, "DELETE")\n    (OPTIONS,"OPTIONS")\n    (HEAD,   "HEAD")\n    (TRACE,  "TRACE");\n

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现在如果我打电话

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requestToString.at(GET);\n

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it\xc2\xb4s 好的，但是如果我调用一个不存在的密钥，例如

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requestToString.at(THIS_IS_NO_KNOWN_KEY);\n

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它给出了运行时异常并且整个过程中止..

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防止这种情况的最好方法是什么？是否有一个编译指示或什么，或者我应该“像java一样”用try/catch块或什么包围它？

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亲切的亚历克斯

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Answer 1

如果您希望在未找到异常时使用at该异常，如果您不希望它终止进程，则在某处处理该异常；find如果你想在本地处理它，请使用：

auto found = requestToString.find(key);
if (found != requestToString.end()) {
    // Found it
    do_something_with(found->second);
} else {
    // Not there
    complain("Key was not found");
}