\u6700\u8fd1\u5728\u6298\u817e\u4e00\u4e9b\u6027\u80fd\u4f18\u5316\u7684\u4e8b\u513f, \u987a\u4fbf\u8bb0\u5f55\u4e00\u4e0b<\/p>\n
\u5f53\u7136, \u70c2\u5927\u8857\u7684\u6284\u6765\u6284\u53bb\u6700\u6ca1\u610f\u601d\u4e86, \u8fd9\u91cc\u4e00\u5982\u65e2\u5f80\u7684\u5217\u4e00\u4e9b\u4e0d\u5e38\u89c1\u7684\u72b6\u51b5<\/p>\n
\u8fd9\u4e2a\u5176\u5b9e\u662f\u4e2a\u633a\u6709\u610f\u601d\u7684\u8bdd\u9898, \u8fd9\u91cc\u4e0d\u7ec6\u8bb2, \u6709\u5174\u8da3\u8bf7\u5148\u81ea\u884c\u641c\u7d22 "\u5206\u652f\u9884\u6d4b" \u5b66\u4e60\u4e00\u4e0b<\/p>\n
\u5178\u578b\u793a\u4f8b\u662f: \u5bf9\u4e00\u4e2a\u5df2\u6392\u5e8f\u7684\u6570\u7ec4\u505a if else \u904d\u5386, \u660e\u663e\u5feb\u4e8e\u4e00\u4e2a\u672a\u6392\u5e8f\u7684\u6570\u7ec4<\/p>\n
\u4e0d\u8fc7\u901a\u5e38\u6bd4\u8f83\u5c11\u9047\u5230\u4e0a\u8ff0\u60c5\u5f62, \u8fd9\u8fb9\u5217\u4e00\u4e2a\u7ecf\u5e38\u80fd\u78b0\u5230\u7684\u7ec6\u8282:<\/p>\n
\/\/ \u793a\u4f8b1\nT func() {\n if(cond) {\n return a;\n }\n return b;\n}\n\n\/\/ \u793a\u4f8b2\nT func() {\n if(cond) {\n return a;\n }\n else {\n return b;\n }\n}<\/code><\/pre>\n\u901a\u5e38\u60c5\u51b5\u4e0b, \u793a\u4f8b2 \u6bd4\u793a\u4f8b1 \u8981\u5feb (\u5927\u7ea6 5%~10%),
\n\u56e0\u4e3a\u5982\u679c\u4e0d\u5728 else \u4e2d, return b;<\/code> \u5c06\u4f5c\u4e3a\u72ec\u7acb\u8bed\u53e5, \u4e0d\u53c2\u4e0e\u5206\u652f\u9884\u6d4b<\/p>\ndynamic_cast \u4e0e\u865a\u51fd\u6570<\/h1>\n
\u901a\u5e38\u60c5\u51b5\u4e0b, \u865a\u51fd\u6570\u8c03\u7528\u53ea\u6bd4\u666e\u901a\u51fd\u6570\u8c03\u7528\u7565\u5fae\u6162\u4e00\u70b9 (\u591a\u4e86\u4e00\u4e2a\u865a\u8868\u95f4\u63a5\u5bfb\u5740\u7684\u6b65\u9aa4)<\/p>\n
\u4e0d\u8fc7 dynamic_cast \u5c31\u4e0d\u540c\u4e86, \u5f80\u5f80\u9700\u8981\u904d\u5386\u7ee7\u627f\u6811, \u5c24\u5176\u5728\u591a\u7ee7\u627f\u548c\u865a\u7ee7\u627f\u7684\u65f6\u5019, \u6027\u80fd\u76f8\u5f53\u7cdf\u7cd5<\/p>\n
\u67d0\u4e9b\u5bf9\u6027\u80fd\u8981\u6c42\u9ad8\u7684\u573a\u5408, \u5982\u679c\u80fd\u591f\u660e\u786e\u7ee7\u627f\u5173\u7cfb\u548c\u7236\u5b50\u7c7b\u7684\u903b\u8f91\u5173\u7cfb, \u5c31\u9700\u8981\u5404\u79cd\u59ff\u52bf\u7ed5\u5f00 dynamic_cast \u4e86<\/p>\n
\n- \n
\u59ff\u52bf1<\/p>\n
class Base {\n virtual ChildA *toChildA(void) {return NULL;}\n virtual ChildB *toChildB(void) {return NULL;}\n};\nclass ChildA : public Base {\n virtual ChildA *toChildA(void) {\n return this;\n }\n};\nclass ChildB : public Base {\n virtual ChildB *toChildB(void) {\n return this;\n }\n};<\/code><\/pre>\n\u6bd4\u8f83\u901a\u7528, \u51e0\u4e4e\u6ca1\u5565\u526f\u4f5c\u7528\u548c\u5751, \u4e0d\u8fc7\u7528\u8d77\u6765\u4e0d\u662f\u5f88\u7075\u6d3b, \u9002\u7528\u4e8e\u7236\u7c7b\u660e\u786e\u77e5\u9053\u5b50\u7c7b\u7c7b\u578b\u7684\u60c5\u51b5,
\n\u5178\u578b\u573a\u666f: \u7f51\u7edc\u6a21\u5757\u4e2d\u5404\u79cd Message \u7c7b\u578b<\/p>\n<\/li>\n
- \n
\u59ff\u52bf2:<\/p>\n
Child *child = isChildType(base) ? static_cast(base) : NULL;<\/code><\/pre>\n\u7075\u6d3b\u4f46\u662f\u5751\u4e5f\u5f88\u5927, isChildType \u672c\u8eab\u5c31\u6709\u5f88\u591a\u5b66\u95ee, static_cast \u66f4\u662f\u6709\u8bb2\u7a76\u4e0d\u80fd\u968f\u4fbf\u7528\u7684,
\n\u5178\u578b\u60c5\u51b5\u5c31\u662f\u591a\u7ee7\u627f\u4e2d\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528, \u6709\u5174\u8da3\u7684\u53ef\u4ee5\u53bb\u4e86\u89e3\u4e0b C\u8279 \u7684\u5bf9\u8c61\u5185\u5b58\u5e03\u5c40, \u5c31\u660e\u767d\u4e86<\/p>\n