{"id":607,"date":"2012-07-27T23:54:18","date_gmt":"2012-07-27T15:54:18","guid":{"rendered":"http:\/\/newbiecoder.0ginr.com\/blog\/?p=607"},"modified":"2012-08-05T00:58:31","modified_gmt":"2012-08-04T16:58:31","slug":"%e4%b8%ba%e4%bb%80%e4%b9%88%e4%b8%8d%e8%83%bd%e5%9c%a8-for_each-%e4%b8%ad%e4%bd%bf%e7%94%a8-stdcout","status":"publish","type":"post","link":"https:\/\/newbiecoder.0ginr.com\/blog\/?p=607","title":{"rendered":"\u4e3a\u4ec0\u4e48\u4e0d\u80fd\u5728 for_each \u4e2d\u4f7f\u7528 std::cout << boost::lambda::_1 << std::endl;"},"content":{"rendered":"

C++ 11 \u5df2\u7ecf\u539f\u751f\u652f\u6301\u4e86 lambda \u8868\u8fbe\u5f0f\u3002\u5982\u679c\u771f\u7684\u9700\u8981\u6807\u9898\u4e2d\u7684\u5199\u6cd5\uff0c\u8bf7\u8003\u8651\u4f7f\u7528\u539f\u751f\u7684 lambda \u8868\u8fbe\u5f0f\u3002<\/em><\/p>\n

\u867d\u7136\u8bf4\u5728 for_each(begin, end, functor) \u4e2d\uff0cfunctor \u4e0d\u80fd\u4f7f\u7528
\nstd::cout << boost::lambda::_1 << std::endl<\/code>
\n\u7684\u5199\u6cd5\uff0c\u4f46\u662f\u6beb\u65e0\u7591\u95ee\uff0c\u4f7f\u7528
\nstd::cout << boost::lambda::_1 << "\\n"<\/code>
\n\u662f\u6ca1\u6709\u95ee\u9898\u7684\u3002<\/p>\n

\u8fd9\u4e2a\u521d\u770b\u8d77\u6765\u53ef\u80fd\u5f88\u5947\u602a\u3002\u5b9e\u9645\u4e0a\u539f\u56e0\u662f\u8fd9\u6837\u7684\u3002<\/p>\n

\u5728\u6211\u7684 MSVC++ 2012 RC \u7684 STL \u4e2d\uff0cstd::endl \u7684\u5b9a\u4e49\u662f\u8fd9\u6837\u7684\uff08\u7ecf\u8fc7\u7b80\u5316\uff09\uff1a
\n

ostream& endl(ostream& os) {\n  os.put('\\n');\n  os.flush();\n  return os;\n}\n\nwostream& endl(wostream& os) {\n  os.put('\\n');\n  os.flush();\n  return os;\n}<\/code><\/pre>
\n\u8bf7\u6ce8\u610f\u8fd9\u513f endl \u662f\u88ab\u91cd\u8f7d\u4e86\u7684\uff08\u5b9e\u9645\u4e0a\u8fd8\u6709\u66f4\u591a\u91cd\u8f7d\u7248\u672c\uff0c\u8fd9\u513f\u53ea\u5217\u51fa\u6765\u4e24\u4e2a\uff0c\u53ef\u4ee5\u8bf4\u660e\u95ee\u9898\u5373\u53ef\u3002\uff09\u3002<\/p>\n
\u800c std::basic_ostream \uff08std::ostream \/ std::wostream \u5b9e\u9645\u4e0a\u662f\u5bf9 std::basic_ostream \u5b9e\u4f8b\u5316\u7684\u7ed3\u679c\uff09\u4e2d\u5bf9 operator << \u6709\u8fd9\u4e48\u4e00\u4e2a\u91cd\u8f7d\u7248\u672c\uff08\u7ecf\u8fc7\u7b80\u5316\uff09\uff1a\n
basic_ostream<x, y> operator << (basic_ostream<x, y>& (__cdecl *func)(basic_ostream<x, y>&)) {\n  return (func(*this));\n}<\/code><\/pre>\n\n\u8fd9\u6837\uff0c\u5f53\u78b0\u5230\nstd::cout << std::endl; <\/code>\n\u5c31\u6839\u636e std::cout \u7684\u7c7b\u578b\u628a wchar_t \u7b49\u7b49\u7684 std::endl \u5426\u5b9a\u6389\uff0c\u8fd9\u6837\u5c31\u53ea\u6709 char \u7c7b\u578b\u7684 std::endl \u53ef\u9009\u3002\n\u4e8e\u662f\u8c03\u7528\u4e86 std::endl \u8fd9\u4e2a\u51fd\u6570\uff0c\u7136\u540e\u8f93\u51fa\u6362\u884c\u5e76\u5237\u65b0\u7f13\u51b2\u533a\u3002\n\n\u800c\u5230\u4e86\nstd::cout << boost::lambda::_1 << std::endl;<\/code>\n\u8fd9\u513f\uff0c\u60c5\u51b5\u5c31\u5b8c\u5168\u4e0d\u4e00\u6837\u4e86\u3002\n\n\u9996\u5148\uff0c\u4e3a\u4e86\u80fd\u591f\u8ba9\nstd::cout << boost::lambda::_1<\/code>\n\u751f\u6210\u4e00\u4e2a functor \u6765\u8ba9 for_each \u63a5\u53d7\u5b83\uff0cboost \u5e93\u6709\u7c7b\u4f3c\u8fd9\u6837\u7684\u91cd\u8f7d\uff08\u7ecf\u8fc7\u7b80\u5316\uff09\uff1a\n
lambda_functor<...> operator << (ostream& os, lambda_functor<...>& arg) {\n  ...\n}<\/code><\/pre>\n\u5176\u4e2d lambda_functor \u6b63\u662f boost::lambda::_1 \u7684\u7c7b\u578b\u3002\n\n\u8fd9\u4e2a\u91cd\u8f7d\u7248\u672c\u5b9e\u9645\u4e0a\u662f\u8fd4\u56de\u4e86\u4e00\u4e2a lambda_functor_base \u7c7b\u578b\u7684\u5bf9\u8c61\uff0c\u56e0\u6b64\nstd::cout << boost::lambda::_1;<\/code>\n\u5b9e\u9645\u4e0a\u4f1a\u6784\u9020\u4e00\u4e2a lambda_functor_base \u7c7b\u578b\u7684\u5bf9\u8c61\u4f20\u7ed9 for_each\uff0c\u8fd9\u6837\u5982\u4e0b\u7684\u4ee3\u7801\u5c31\u53ef\u4ee5\u7f16\u8bd1\u901a\u8fc7\u4e86\uff1a\nstd::for_each(begin, end, std::cout << boost::lambda::_1);<\/code>\n\n\u90a3\u4e48 boost::lambda \u4e2d\u90a3\u4e2a\u91cd\u8f7d\u7248\u672c\u7684 operator << \u7a76\u7adf\u6784\u9020\u6210\u4e86\u4ec0\u4e48\u6837\u7684\u5bf9\u8c61\u5462\uff1f\u662f\u8fd9\u6837\u7684\uff1a\n
boost::lambda::lambda_functor<\n  boost::lambda::lambda_functor_base<\n    boost::lambda::bitwise_action<\n      boost::lambda::leftshift_action\n    >,\n    boost::tuples::tuple<\n      std::basic_ostream<char, std::char_traits<char>> &,\n      boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type,\n      boost::tuples::null_type\n  \n    >\n  >\n><\/code><\/pre>\n\u5f88\u9057\u61be\uff0c\u5b83\u6ca1\u6709\u9488\u5bf9 ostream \u6240\u4f7f\u7528\u7684 std::endl \u7684\u7c7b\u578b\uff0c\u4e5f\u5c31\u662f\uff1a\nstd::basic_ostream<char, std::char_traits<char>>& (endl_type)(std::basic_ostream<char, std::char_traits<char>>&)<\/code>\n\u4e13\u95e8\u91cd\u8f7d operator <<\uff0c\u6240\u4ee5\u7f16\u8bd1\u5668\u5c31\u65e0\u4ece\u5f97\u77e5\u8be5\u7528\u54ea\u4e2a std::endl\uff0c\u8fdb\u800c\u4ea7\u751f\u4e86\u7f16\u8bd1\u9519\u8bef\u3002\n\n\u5f53\u7136\uff0c\u5982\u679c\u6211\u4eec\u544a\u8bc9\u7f16\u8bd1\u5668\u6211\u4eec\u9700\u8981\u7528\u7684 std::endl \u662f\u54ea\u4e2a\u7248\u672c\uff0c\u90a3\u4e48\u4e5f\u5c31\u4e0d\u4f1a\u51fa\u73b0\u95ee\u9898\u4e86\u3002\u5c31\u50cf\u8fd9\u6837\uff08\u6211\u8fd9\u513f\u7684 ostream \u6240\u4f7f\u7528\u7684 std::endl \u662f std::ostream& (*)(std::ostream&) \u7c7b\u578b\u7684\uff09\uff1a\nstd::for_each(begin, end, std::cout << boost::lambda::_1 << (std::ostream& (*)(std::ostream&))std::endl);<\/code>\n\n\u5982\u679c\u4ece\u6280\u672f\u4e0a\uff0c\u5355\u72ec\u9488\u5bf9\nstd::cout << boost::lambda::_1 << std::endl<\/code>\n\u8fd9\u6837\u7684\u8bed\u53e5\u505a\u4e00\u4e2a\u91cd\u8f7d\u7248\u672c\uff0c\u6211\u89c9\u5f97\u5e94\u8be5\u662f\u53ef\u884c\u7684\uff0c\u4f46\u662f\u4e00\u65b9\u9762\uff0c\u5728\u5b9e\u9645\u4f7f\u7528\u4e2d\u8fd8\u6709\u7c7b\u4f3c\u4e8e\nstd::cout << boost_lambda::_1 << 1 << ... << std::endl<\/code>\n\u8fd9\u79cd\u8bed\u53e5\uff0c\u53e6\u5916\u4e00\u65b9\u9762\u636e\u8bf4 GCC \u4e0b\u9762 std::endl \u662f\u4f5c\u4e3a\u4e00\u4e2a\u6a21\u677f\u51fd\u6570\u5b9e\u73b0\u7684\uff0c\u6240\u4ee5\u8981\u628a\u6240\u6709\u60c5\u51b5\u5168\u90e8\u5904\u7406\u6389\u53ef\u80fd\u5c31\u4f1a\u5b58\u5728\u95ee\u9898\u3002\n\u53e6\u5916\uff0c\u5982\u4f55\u628a ostream \u4f7f\u7528\u7684 std::endl \u8ddf wostream \u4f7f\u7528\u7684 std::endl \u533a\u5206\u5f00\u4e5f\u662f\u4e00\u4e2a\u95ee\u9898\u3002\n\n\u5f53\u7136\uff0c\u73b0\u5728 C++ 11 \u6709\u4e86\u539f\u751f\u7684 lambda \u652f\u6301\uff0c\u8fd9\u4e48\u5199\u5c31\u53ef\u4ee5\u4e86\uff1a\n
std::for_each(begin, end, [] (type value) {\n  std::cout << value << std::endl;\n}<\/code><\/pre>\n<\/p>\n","protected":false},"excerpt":{"rendered":"
C++ 11 \u5df2\u7ecf\u539f\u751f\u652f\u6301\u4e86 lambda \u8868\u8fbe\u5f0f\u3002\u5982\u679c\u771f\u7684\u9700\u8981\u6807\u9898\u4e2d\u7684\u5199\u6cd5\uff0c\u8bf7\u8003\u8651\u4f7f\u7528\u539f\u751f\u7684 lambda  […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-607","post","type-post","status-publish","format-standard","hentry","category-1"],"_links":{"self":[{"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/607","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=607"}],"version-history":[{"count":14,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/607\/revisions"}],"predecessor-version":[{"id":630,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/607\/revisions\/630"}],"wp:attachment":[{"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=607"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=607"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/newbiecoder.0ginr.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=607"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}