{"id":200899,"date":"2020-11-24T07:42:22","date_gmt":"2020-11-23T23:42:22","guid":{"rendered":"http:\/\/4563.org\/?p=200899"},"modified":"2020-11-24T07:42:22","modified_gmt":"2020-11-23T23:42:22","slug":"%e6%b1%82%e6%95%99%e4%b8%80%e4%b8%aa-c%e8%af%ad%e6%b3%95%e9%97%ae%e9%a2%98-%e8%bf%99%e6%ae%b5%e4%bb%a3%e7%a0%81%e4%b8%ba%e4%bd%95%e5%8f%aa%e6%9e%90%e6%9e%84%e4%b8%80%e6%ac%a1%e5%91%a2","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=200899","title":{"rendered":"\u6c42\u6559\u4e00\u4e2a c++\u8bed\u6cd5\u95ee\u9898, \u8fd9\u6bb5\u4ee3\u7801\u4e3a\u4f55\u53ea\u6790\u6784\u4e00\u6b21\u5462"},"content":{"rendered":"
\n
\n
\n

\u6c42\u6559\u4e00\u4e2a c++\u8bed\u6cd5\u95ee\u9898, \u8fd9\u6bb5\u4ee3\u7801\u4e3a\u4f55\u53ea\u6790\u6784\u4e00\u6b21\u5462 <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : jdz <\/span> <\/i> 2<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
class excption_test
{
public:
excption_test();
~excption_test();
};<\/p>\n

excption_test::excption_test()
{
std::cout << “in constructorn”;
}<\/p>\n

excption_test::~excption_test()
{
std::cout << “auto in destructor??n”;
}<\/p>\n

excption_test get_ex()
{
excption_test c;
return c;
}<\/p>\n

int main()
{
excption_test m = get_ex();
return 0;
}<\/p>\n

\u6211\u7406\u89e3 get_ex()\u51fd\u6570\u4e2d\u521b\u5efa\u4e86\u4e00\u4e2a\u5bf9\u8c61, \u79bb\u5f00\u6808\u7684\u65f6\u5019\u4f1a\u8fdb\u884c\u6790\u6784, \u6790\u6784 c \u5bf9\u8c61, \u540c\u65f6\u8c03\u7528\u62f7\u8d1d\u6784\u9020\u51fd\u6570\u62f7\u8d1d\u7ed9 main \u51fd\u6570\u4e2d\u7684 m \u53d8\u91cf, \u5728 main \u51fd\u6570\u7ed3\u675f\u7684\u65f6\u5019\u518d\u6790\u6784 m \u5bf9\u8c61 <\/p><\/div>\n

\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (11<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : hello2060 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5f88\u4e45\u6ca1\u6709\u641e c++\u5df2\u7ecf\u60f3\u4e0d\u8d77\u6765\u4e86\uff0c\u4f60\u8fd9\u4e2a getex()\u5bf9\u5417\uff0c\u786e\u5b9a\u8fd9\u79cd\u5199\u6cd5\u6ca1\u5565\u95ee\u9898\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : hello2060 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u662f\u53ea\u76f4\u63a5\u8fd4\u56de\u4e00\u4e2a\u6808\u4e0a\u5bf9\u8c61 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : hello2060 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5982\u679c\u53ef\u4ee5\u7684\u8bdd\u770b\u770b\u6709\u7f16\u8bd1\u5668\u4f18\u5316\u5417 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : jdz <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @hello2060 \u662f\u5bf9\u7684\uff0c\u6211\u6d4b\u8bd5\u8fc7\u3002\u53e6\u5916\u4e0d\u592a\u4f1a\u770b\u7f16\u8bd1\u5668\u4f18\u5316\uff0c\u6211\u89c9\u7684\u7f16\u8bd1\u5668\u4f18\u5316\u4e0d\u4f1a\u6539\u53d8\u7a0b\u5e8f\u6267\u884c\u7ed3\u679c <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : codehz <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @jdz RVO \u662f\u5f3a\u5236\u7684\uff0cNRVO \u662f\u53ef\u9009\u7684\uff0c\u5177\u4f53\u5185\u5bb9\u81ea\u5df1\u641c\u7d22 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : twoconk <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4e0a\u662f\u6b63\u89e3\uff0c\u5b9e\u9645\u9879\u76ee\u4e2d\u901a\u5e38\u8fd4\u56de\u5806\u5185\u5b58\uff0cRVO \u5373\u8fd4\u56de\u503c\u4f18\u5316\uff0c\u53ef\u4ee5\u5c11\u505a\u4e00\u6b21\u62f7\u8d1d\u6784\u9020\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zhuangzhuang1988 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u8fd9\u4e2a\u76f4\u63a5\u770b <\u6df1\u5165\u7406\u89e3 C++\u5bf9\u8c61\u6a21\u578b>
    \u91cc\u9762\u6709\u5f88\u591a\u5173\u4e8e \u8fd9\u6837\u7684\u9898\u76ee
    \u600e\u4e48\u91cd\u5199 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : sfqtsh <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    See https:\/\/en.wikipedia.org\/wiki\/Copy_elision<\/p>\n

    g++\u4f60\u53ef\u4ee5\u52a0\u9009\u9879 -fno-elide-constructors \u53d6\u6d88\u4f18\u5316 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : nightwitch <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u89e6\u53d1\u4e86\u7f16\u8bd1\u5668\u4f18\u5316\u5457\uff0c\u4e0d\u4e00\u5b9a\u662f RVO\uff0c\u6709\u53ef\u80fd get_ex()\u51fd\u6570\u6574\u4e2a\u90fd\u88ab inline \u4e86\uff0c\u5b9e\u9645\u4e0a\u7684\u51fd\u6570\u4f53\u662f
    int main(){
    excption_test m;
    return 0;
    } <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : nightwitch <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5728 g++10.2\uff0c\u5f00\u6700\u9ad8\u7ea7\u522b\u7684\u4f18\u5316\uff0c\u4f60\u7684\u4ee3\u7801\u5b9e\u9645\u4e0a\u88ab\u7f16\u8bd1\u6210\u4e86<\/p>\n

    int main()
    {
    std::cout << “in constructorn”;
    std::cout << “auto in destructor??n”;
    return 0;
    }<\/p>\n

    \u89c1 https:\/\/godbolt.org\/z\/14o3WY <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : 0x11901 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @nightwitch \u7f16\u8bd1\u5668\u6bd4\u6211\u4f1a\u5199\u4ee3\u7801\u7cfb\u5217 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    \u6c42\u6559\u4e00\u4e2a c++\u8bed\u6cd5\u95ee\u9898, \u8fd9\u6bb5\u4ee3…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/200899"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=200899"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/200899\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=200899"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=200899"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=200899"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}