auto\u6545\u540d\u610f\u4e49\u81ea\u52a8\u63a8\u5bfc，\u6ca1\u4ec0\u4e48\u592a\u7279\u522b\u7684，\u53ef\u4ee5\u81ea\u884c\u4e86\u89e3\u4e00\u4e0bc++\u7684auto\u5173\u952e\u5b57\u662f\u4ec0\u4e48<\/p>\n
decltype \u5982\u679c\u4e0d\u4e86\u89e3\u7684，\u53ef\u4ee5\u770b\u8fd9\u7bc7\u6587\u7ae0：c++\u7684decltype\u662f\u4ec0\u4e48<\/p>\n
\u5982\u679c\u6ca1\u6709\u6df1\u5165\u4e86\u89e3，\u4f1a\u611f\u89c9\u4e24\u8005\u597d\u50cf\u4f5c\u7528\u662f\u5f88\u7c7b\u4f3c\u7684，\u5176\u5b9eauto \u548c decltype \u867d\u7136\u90fd\u505a\u201c\u7c7b\u578b\u63a8\u5bfc\u201d，\u4f46\u76ee\u6807\u548c\u89c4\u5219\u4e0d\u540c，\u4e0d\u80fd\u4e92\u76f8\u66ff\u4ee3\u3002<\/p>\n
auto \u4e3b\u8981\u7528\u4e8e：<\/p>\n
int main() {
\n auto x = 1;
\n return 0;
\n} <\/p>\n
\u5b83\u7684\u63a8\u5bfc\u89c4\u5219\u63a5\u8fd1\u6a21\u677f\u6309\u503c\u4f20\u53c2，\u4f1a\u4e22\u5f03\u5f15\u7528\u548c\u9876\u5c42 const，\u6570\u7ec4\/\u51fd\u6570\u53ef\u80fd\u9000\u5316\u4e3a\u6307\u9488：<\/p>\n
int n = 0;
\nint& r = n;
\nconst int c = 1;<\/p>\n
auto a = r; \/\/ a \u662f int，\u4e0d\u662f int&
\nauto b = c; \/\/ b \u662f int，const \u4e22\u4e86 <\/p>\n
\u6240\u4ee5 auto \u9002\u5408\u201c\u6211\u8981\u4e00\u4e2a\u53d8\u91cf，\u503c\u62f7\u8d1d\u51fa\u6765，\u7c7b\u578b\u4f60\u5e2e\u6211\u63a8\u201d\u3002<\/p>\n
\u8fd9\u91cc\u6709\u4e00\u4e2a\u6982\u5ff5：\u9876\u5c42const\u548c\u5e95\u5c42const<\/p>\n
\u53ef\u89c1\u8fd9\u7bc7\u6587\u4ef6：\u4ec0\u4e48\u662f\u9876\u5c42 const\u4ec0\u4e48\u662f\u5e95\u5c42const<\/p>\n
decltype(expr) \u4e0d\u5b9a\u4e49\u53d8\u91cf，\u4e5f\u4e0d\u9700\u8981\u521d\u59cb\u5316，\u66f4\u4e0d\u4f1a\u6c42\u503c：<\/p>\n
decltype(r) d = n; \/\/ d \u662f int&
\ndecltype(c) e = c; \/\/ e \u662f const int
\ndecltype((n)) f = n; \/\/ f \u662f int&，\u56e0\u4e3a (n) \u662f\u5de6\u503c\u8868\u8fbe\u5f0f <\/p>\n
\u5b83\u4fdd\u7559\u5f15\u7528\u548c cv \u9650\u5b9a，\u89c4\u5219\u5927\u81f4\u662f：<\/p>\n
decltype(\u53d8\u91cf\u540d)：\u5f97\u5230\u53d8\u91cf\u58f0\u660e\u65f6\u7684\u7c7b\u578b；<\/p>\n<\/li>\n
decltype(\u5de6\u503c\u8868\u8fbe\u5f0f)：\u901a\u5e38\u5f97\u5230 T&；<\/p>\n<\/li>\n
decltype(\u53f3\u503c\u8868\u8fbe\u5f0f)：\u5f97\u5230 T\u3002<\/p>\n<\/li>\n<\/ul>\n
int n = 0;
\nint& r = n;<\/p>\n
auto x = r; \/\/ int
\ndecltype(r) y = n; \/\/ int& <\/p>\n
auto \u66f4\u50cf\u201c\u590d\u5236\u4e00\u4e2a\u503c\u51fa\u6765\u201d，decltype \u66f4\u50cf\u201c\u95ee\u7f16\u8bd1\u5668：\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u5230\u5e95\u662f\u4ec0\u4e48\u7c7b\u578b\u201d\u3002<\/p>\n
template <class T, class U>
\nauto add(T t, U u) -> decltype(t + u) {
\n return t + u;
\n} <\/p>\n
\u8fd9\u91cc\u8fd4\u56de\u7c7b\u578b\u4f9d\u8d56\u53c2\u6570\u8868\u8fbe\u5f0f t + u，auto \u5355\u72ec\u505a\u4e0d\u5230\u3002<\/p>\n
decltype(std::declval<T>().foo()) <\/p>\n
\u7528\u4e8e\u83b7\u53d6\u67d0\u4e2a\u8868\u8fbe\u5f0f\u7684\u7ed3\u679c\u7c7b\u578b\u3002<\/p>\n
template <class Container>
\nauto front(Container& c) -> decltype(c.front()) {
\n return c.front();
\n} <\/p>\n
\u5982\u679c front() \u8fd4\u56de\u5f15\u7528，\u8fd4\u56de\u7c7b\u578b\u4e5f\u4fdd\u7559\u5f15\u7528\u3002<\/p>\n
decltype(auto) f() {
\n int x = 0;
\n return (x); \/\/ \u8fd4\u56de int&
\n} <\/p>\n
auto \u4f1a\u8fd4\u56de\u503c，decltype(auto) \u53ef\u4ee5\u4fdd\u7559\u5f15\u7528\u3002<\/p>\n
auto：\u5b9a\u4e49\u53d8\u91cf\u65f6，\u6309\u503c\u63a8\u5bfc\u4e00\u4e2a\u65b9\u4fbf\u7684\u7c7b\u578b，\u4f1a\u4e22\u5f15\u7528\/\u9876\u5c42 const\u3002<\/p>\n<\/li>\n
decltype：\u67e5\u8be2\u8868\u8fbe\u5f0f\u7684\u7cbe\u786e\u7c7b\u578b，\u4fdd\u7559\u5f15\u7528\u548c cv，\u4e0d\u6c42\u503c\u3002<\/p>\n<\/li>\n
\u4e8c\u8005\u662f\u4e92\u8865\u5173\u7cfb：auto \u8d1f\u8d23\u201c\u58f0\u660e\u53d8\u91cf\u201d，decltype \u8d1f\u8d23\u201c\u7c7b\u578b\u8ba1\u7b97\/\u7cbe\u786e\u83b7\u53d6\u7c7b\u578b\u201d\u3002<\/p>\n<\/li>\n<\/ul>\n
\u6240\u4ee5\u4e0d\u662f\u6709\u4e86 auto \u5c31\u4e0d\u9700\u8981 decltype，\u800c\u662f\u5f88\u591a\u573a\u666f auto \u6839\u672c\u8868\u8fbe\u4e0d\u4e86，\u4f8b\u5982\u4fdd\u7559\u5f15\u7528\u3001\u5c3e\u7f6e\u8fd4\u56de\u7c7b\u578b\u3001\u6a21\u677f\u4e2d\u63a8\u5bfc\u8868\u8fbe\u5f0f\u7c7b\u578b\u7b49\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
auto\u6545\u540d\u610f\u4e49\u81ea\u52a8\u63a8\u5bfc，\u6ca1\u4ec0\u4e48\u592a\u7279\u522b\u7684，\u53ef\u4ee5\u81ea\u884c\u4e86\u89e3\u4e00\u4e0bc\u7684auto\u5173\u952e\u5b57\u662f\u4ec0\u4e48
\ndecltype \u5982\u679c\u4e0d\u4e86\u89e3\u7684，\u53ef\u4ee5\u770b\u8fd9\u7bc7\u6587\u7ae0：c\u7684decltype\u662f\u4ec0\u4e48
\n\u5982\u679c\u6ca1\u6709\u6df1\u5165\u4e86\u89e3，\u4f1a\u611f\u89c9\u4e24\u8005\u597d\u50cf\u4f5c\u7528\u662f\u5f88\u7c7b\u4f3c\u7684，\u5176\u5b9eauto \u548c decltype \u867d\u7136\u90fd\u505a\u201c\u7c7b\u578b\u63a8\u5bfc\u201d，\u4f46\u76ee\u6807\u548c\u89c4\u5219\u4e0d\u540c，\u4e0d\u80fd\u4e92\u76f8\u66ff\u4ee3\u3002
\n1. auto \u662f\u5b9a\u4e49\u53d8\u91cf\u65f6\u7684\u7c7b\u578b\u63a8\u5bfc
\nauto \u4e3b\u8981\u7528\u4e8e&<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[55,190],"topic":[],"class_list":["post-120656","post","type-post","status-publish","format-standard","hentry","category-server","tag-c","tag-190"],"yoast_head":"\n