{"id":1963,"date":"2016-04-10T20:33:41","date_gmt":"2016-04-10T12:33:41","guid":{"rendered":"http:\/\/boweihe.me\/?p=1963"},"modified":"2016-04-10T20:33:41","modified_gmt":"2016-04-10T12:33:41","slug":"c%e7%b1%bb%e5%9e%8b%e8%bd%ac%e6%8d%a2%e7%ac%a6-static_cast-dynamic_cast-const_cast","status":"publish","type":"post","link":"https:\/\/dayandcarrot.space\/?p=1963","title":{"rendered":"C++\u7c7b\u578b\u8f6c\u6362\u7b26 static_cast, dynamic_cast, const_cast"},"content":{"rendered":"<p>\u201ccast\u201d\u4e00\u8bcd\u5728\u82f1\u6587\u91cc\u6709\u201c\u6d47\u94f8\u201d\u7684\u610f\u601d\uff0c\u8fd8\u662f\u633a\u5f62\u8c61\u7684\u3002<\/p>\n<h1>1.static_cast<\/h1>\n<p>\u53ef\u4ee5\u770b\u505a\u662f\u5229\u7528\u4e00\u4e2a\u539f\u59cb\u503c\u6784\u5efa\u4e00\u4e2a\u4e34\u65f6\u5bf9\u8c61\uff0c\u5e76\u518d\u8bbe\u5b9a\u521d\u59cb\u503c\u7684\u65f6\u5019\u4f7f\u7528\u7c7b\u578b\u8f6c\u6362\u3002<br \/>\n\u4f8b\u5982\uff1a<\/p>\n<pre class=\"lang:c++ decode:true \">float x;\n...\ncout &lt;&lt; static_cast&lt;int&gt;(x); \/\/float to int\n...\ncout &lt;&lt; static_cast&lt;string&gt;(\"hello\")); \/\/char* to string<\/pre>\n<h1>2.dynamic_cast<\/h1>\n<p>\u5c06\u591a\u6001\u7c7b\u578b(polymorphic type)\u6210\u5458\u5411\u4e0b\u8f6c\u6362\u4e3a\u5176\u5bf9\u5e94\u7684\u9759\u6001\u7c7b\u578b\u6210\u5458\u3002\u8fd9\u4e2acast\u662f\u5728\u8fd0\u884c\u65f6\u5b9e\u65f6\u68c0\u9a8c\u7684\uff0c\u56e0\u6b64\u53ef\u4ee5\u7528\u6765\u68c0\u6d4b\u67d0\u4e2a\u6307\u9488\u6307\u5411\u7684\u5bf9\u8c61\u5230\u5e95\u662f\u4e0d\u662fXXX\u7c7b\u7684\u3002<\/p>\n<pre class=\"lang:c++ decode:true \">class Car; \/\/abstract class\nclass Cabriolet : public Car {...};\nclass Limousine : public Car {...};\nvoid f(Car* cp){\n    Cabriolet* p = dynamic_cast&lt;Cabriolet*&gt;(cp);\n    if(p == NULL) {\n        \/\/cp is not referred to an object of Cabriolet\n    }\n}<\/pre>\n<p>\u5f53\u53c2\u6570\u662f\u4e2a\u5f15\u7528\uff0c\u5e76\u4e14\u7c7b\u522b\u8f6c\u6362\u5931\u8d25\u7684\u65f6\u5019\uff0c\u4f1a\u629b\u51fabad_cast\u5f02\u5e38\u54e6\u3002<\/p>\n<h1>3.const_cast<\/h1>\n<p>\u53bb\u9664\u67d0\u4e2a\u5bf9\u8c61\u7684const\u4fee\u9970\u4f5c\u7528\uff0c\u4e5f\u53ef\u4ee5\u62ff\u6765\u53bb\u9664volatile\u4fee\u9970\u4f5c\u7528\u3002<br \/>\n&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u201ccast\u201d\u4e00\u8bcd\u5728\u82f1\u6587\u91cc\u6709\u201c\u6d47\u94f8\u201d\u7684\u610f\u601d\uff0c\u8fd8\u662f\u633a\u5f62\u8c61\u7684\u3002 1.static_cast \u53ef\u4ee5\u770b\u505a\u662f\u5229\u7528\u4e00\u4e2a\u539f\u59cb\u503c\u6784\u5efa\u4e00\u4e2a\u4e34\u65f6\u5bf9\u8c61\uff0c\u5e76\u518d\u8bbe\u5b9a\u521d\u59cb\u503c\u7684\u65f6\u5019\u4f7f\u7528\u7c7b\u578b\u8f6c\u6362\u3002 \u4f8b\u5982\uff1a float x; &#8230; cout &lt;&lt; static_cast&lt;int&gt;(x); \/\/float to int &#8230; cout &lt;&lt; static_cast&lt;string&gt;(&#8220;hello&#8221;)); \/\/char* to string 2.dynamic_cast \u5c06\u591a\u6001\u7c7b\u578b(polymorphic type)\u6210\u5458\u5411\u4e0b\u8f6c\u6362\u4e3a\u5176\u5bf9\u5e94\u7684\u9759\u6001\u7c7b\u578b\u6210\u5458\u3002\u8fd9\u4e2acast\u662f\u5728\u8fd0\u884c\u65f6\u5b9e\u65f6\u68c0\u9a8c\u7684\uff0c\u56e0\u6b64\u53ef\u4ee5\u7528\u6765\u68c0\u6d4b\u67d0\u4e2a\u6307\u9488\u6307\u5411\u7684\u5bf9\u8c61\u5230\u5e95\u662f\u4e0d\u662fXXX\u7c7b\u7684\u3002 class Car; \/\/abstract class class Cabriolet : public Car {&#8230;}; class Limousine : public Car {&#8230;}; void f(Car* cp){ Cabriolet* p = dynamic_cast&lt;Cabriolet*&gt;(cp); if(p == NULL) { \/\/cp is not referred to [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[28,105],"class_list":["post-1963","post","type-post","status-publish","format-standard","hentry","category-study","tag-c","tag-stl"],"_links":{"self":[{"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=\/wp\/v2\/posts\/1963","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1963"}],"version-history":[{"count":0,"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=\/wp\/v2\/posts\/1963\/revisions"}],"wp:attachment":[{"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1963"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1963"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dayandcarrot.space\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}