{"id":701,"date":"2024-06-02T20:13:12","date_gmt":"2024-06-03T03:13:12","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/dotnet-ch\/?p=701"},"modified":"2024-06-09T23:50:02","modified_gmt":"2024-06-10T06:50:02","slug":"c12%e6%96%b0%e5%8a%9f%e8%83%bd%e5%90%88%e9%9b%86%e4%ba%8c%ef%bc%9a%e4%bd%bf%e7%94%a8%e9%9b%86%e5%90%88%e8%a1%a8%e8%be%be%e5%bc%8f%e9%87%8d%e6%9e%84%e4%bb%a3%e7%a0%81","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/dotnet-ch\/c12%e6%96%b0%e5%8a%9f%e8%83%bd%e5%90%88%e9%9b%86%e4%ba%8c%ef%bc%9a%e4%bd%bf%e7%94%a8%e9%9b%86%e5%90%88%e8%a1%a8%e8%be%be%e5%bc%8f%e9%87%8d%e6%9e%84%e4%bb%a3%e7%a0%81\/","title":{"rendered":"C#12\u65b0\u529f\u80fd\u5408\u96c6\u4e8c\uff1a\u4f7f\u7528\u96c6\u5408\u8868\u8fbe\u5f0f\u91cd\u6784\u4ee3\u7801"},"content":{"rendered":"

\u672c\u6587\u7ffb\u8bd1\u4e8eDavid Pine\u7684\u8fd9\u7bc7\u6587\u7ae0: Refactor your code with C# collection expressions<\/a><\/em>\u3002<\/span><\/p>\n

\u672c\u6587\u662f\u7cfb\u5217\u6587\u7ae0\u7684\u7b2c\u4e8c\u7bc7\uff0c\u8be5\u7cfb\u5217\u6587\u7ae0\u6db5\u76d6\u4e86\u63a2\u7d22<\/span>C# 12<\/span>\u529f\u80fd\u7684\u5404\u79cd\u91cd\u6784\u573a\u666f<\/span>\u3002 <\/span>\u5728\u8fd9\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u4eec\u5c06\u4e86\u89e3\u5982\u4f55\u4f7f\u7528\u96c6\u5408\u8868\u8fbe\u5f0f\u91cd\u6784\u4ee3\u7801\uff0c\u6211\u4eec\u5c06\u5b66\u4e60\u96c6\u5408\u521d\u59cb\u5316\u5668\u3001\u5404\u79cd\u8868\u8fbe\u5f0f\u7528\u6cd5\u3001\u652f\u6301\u7684\u96c6\u5408\u76ee\u6807\u7c7b\u578b\u548c<\/span>spread<\/span>\u8bed\u6cd5\u3002<\/span> \u8be5\u7cfb\u5217\u7684\u8fdb\u5c55\u60c5\u51b5\u5982\u4e0b<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n

    \n
  1. \u4f7f\u7528\u4e3b\u6784\u9020\u51fd\u6570\u91cd\u6784<\/span> C# <\/span>\u4ee3\u7801<\/span><\/a>\u00a0<\/span><\/li>\n
  2. \u4f7f\u7528\u96c6\u5408\u8868\u8fbe\u5f0f\u91cd\u6784<\/span> C# <\/span>\u4ee3\u7801\uff08\u672c\u6587\uff09<\/span>\u00a0<\/span><\/li>\n
  3. \u901a\u8fc7\u4e3a\u4efb\u4f55\u7c7b\u578b\u6dfb\u52a0\u522b\u540d\u6765\u91cd\u6784\u60a8\u7684<\/span> C# <\/span>\u4ee3\u7801<\/span>\u00a0<\/span><\/li>\n
  4. \u91cd\u6784\u60a8\u7684<\/span> C# <\/span>\u4ee3\u7801\u4ee5\u4f7f\u7528\u9ed8\u8ba4<\/span> lambda <\/span>\u53c2\u6570<\/span>\u00a0<\/span><\/li>\n<\/ol>\n

    \u8fd9\u4e9b\u529f\u80fd\u5ef6\u7eed\u4e86\u6211\u4eec\u7684\u65c5\u7a0b\uff0c\u4f7f\u6211\u4eec\u7684\u4ee3\u7801\u66f4\u5177\u53ef\u8bfb\u6027\u548c\u53ef\u7ef4\u62a4\u6027\uff0c\u5e76\u4e14\u88ab\u8ba4\u4e3a\u662f\u5f00\u53d1\u4eba\u5458\u5e94\u8be5\u4e86\u89e3\u7684<\/span>\u201c<\/span>\u65e5\u5e38<\/span> C#\u201d<\/span>\u529f\u80fd<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

    \u96c6\u5408\u8868\u8fbe\u5f0f<\/span><\/b>\ud83c\udfa8<\/span><\/b>\u00a0<\/span><\/p>\n

    C# 12 <\/span>\u5f15\u5165\u4e86\u96c6\u5408\u8868\u8fbe\u5f0f\uff0c\u5b83\u4e3a\u8bb8\u591a\u4e0d\u540c\u7684\u96c6\u5408\u7c7b\u578b\u63d0\u4f9b\u7b80\u5355\u4e14\u4e00\u81f4\u7684\u8bed\u6cd5\u3002<\/span> \u5f53\u4f7f\u7528\u96c6\u5408\u8868\u8fbe\u5f0f\u521d\u59cb\u5316\u96c6\u5408\u65f6\uff0c\u7f16\u8bd1\u5668\u751f\u6210\u7684\u4ee3\u7801\u5728\u529f\u80fd\u4e0a\u4e0e\u4f7f\u7528\u96c6\u5408\u521d\u59cb\u5316\u9879\u7b49\u6548\u3002<\/span> \u8be5\u529f\u80fd\u5f3a\u8c03\u4e00\u81f4\u6027\uff0c\u540c\u65f6\u5141\u8bb8\u7f16\u8bd1\u5668\u4f18\u5316\u4f4e\u7ea7\u7684<\/span> C#\u3002 <\/span>\u5f53\u7136\uff0c\u6bcf\u4e2a\u56e2\u961f\u90fd\u53ef\u4ee5\u51b3\u5b9a\u91c7\u7528\u54ea\u4e9b\u65b0\u529f\u80fd\uff0c\u5982\u679c\u60a8\u613f\u610f\uff0c\u60a8\u53ef\u4ee5\u5c1d\u8bd5\u5e76\u5f15\u5165\u8fd9\u79cd\u65b0\u8bed\u6cd5\uff0c\u56e0\u4e3a\u4e4b\u524d\u6240\u6709\u521d\u59cb\u5316\u96c6\u5408\u7684\u65b9\u6cd5\u90fd\u5c06\u7ee7\u7eed\u5de5\u4f5c<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

    \u5bf9\u4e8e\u96c6\u5408\u8868\u8fbe\u5f0f\uff0c\u5143\u7d20\u51fa\u73b0\u5728\u5de6\u62ec\u53f7<\/span> [ <\/span>\u548c\u53f3\u62ec\u53f7<\/span> ] <\/span>\u4e4b\u95f4\u7684\u5185\u8054\u5143\u7d20\u5e8f\u5217\u3002<\/span> \u7ee7\u7eed\u9605\u8bfb\u4ee5\u4e86\u89e3\u6709\u5173\u96c6\u5408\u8868\u8fbe\u5f0f\u5982\u4f55\u5de5\u4f5c\u7684\u66f4\u591a\u4fe1\u606f<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

    \u521d\u59cb\u5316<\/span><\/b>\ud83c\udf31<\/span><\/b>\u00a0<\/span><\/p>\n

    C# <\/span>\u63d0\u4f9b\u4e86\u8bb8\u591a\u8bed\u6cd5\u6765\u521d\u59cb\u5316\u4e0d\u540c\u7684\u96c6\u5408\u3002<\/span> \u96c6\u5408\u8868\u8fbe\u5f0f\u53d6\u4ee3\u4e86\u6240\u6709\u8fd9\u4e9b\uff0c\u6240\u4ee5\u8ba9\u6211\u4eec\u5148\u6765\u770b\u770b\u521d\u59cb\u5316\u6574\u6570\u6570\u7ec4\u7684\u4e0d\u540c\u65b9\u6cd5\uff0c\u5982\u4e0b\u6240\u793a<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n

    \u8fd9\u56db\u4e2a\u7248\u672c\u5728\u529f\u80fd\u4e0a\u90fd\u662f\u7b49\u6548\u7684\uff0c\u5e76\u4e14\u7f16\u8bd1\u5668\u4e3a\u6bcf\u4e2a\u7248\u672c\u751f\u6210\u76f8\u540c\u7684\u4ee3\u7801\u3002<\/span> \u6700\u540e\u4e00\u4e2a\u793a\u4f8b\u7c7b\u4f3c\u4e8e\u65b0\u7684\u96c6\u5408\u8868\u8fbe\u5f0f\u8bed\u6cd5\u3002<\/span> \u5982\u679c\u60a8\u772f\u8d77\u773c\u775b\uff0c\u5c06\u82b1\u62ec\u53f7<\/span> { <\/span>\u548c<\/span> } <\/span>\u60f3\u8c61\u4e3a<\/span> \u65b9\u62ec\u53f7<\/span> [ <\/span>\u548c<\/span> ]\uff0c<\/span>\u7136\u540e\u60a8\u5c31\u4f1a\u8bfb\u5230\u65b0\u7684\u96c6\u5408\u8868\u8fbe\u5f0f\u8bed\u6cd5\u4e86<\/span>\u3002 <\/span>\u96c6\u5408\u8868\u8fbe\u5f0f\u4e0d\u4f7f\u7528\u82b1\u62ec\u53f7\u3002<\/span> \u8fd9\u662f\u4e3a\u4e86\u907f\u514d\u4e0e\u73b0\u6709\u8bed\u6cd5\u4ea7\u751f\u6b67\u4e49\uff0c\u7279\u522b\u662f\u7528<\/span> { } <\/span>\u6765\u8868\u793a\u6a21\u5f0f\u4e2d\u7684\u4efb\u4f55\u975e\u7a7a<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

    \u6700\u540e\u4e00\u4e2a\u793a\u4f8b\u662f\u552f\u4e00\u663e\u5f0f\u58f0\u660e\u7c7b\u578b\uff0c\u800c\u4e0d\u662f\u4f9d\u8d56<\/span> var\u3002 <\/span>\u4ee5\u4e0b\u793a\u4f8b\u521b\u5efa\u4e00\u4e2a<\/span> List<char>\uff1a<\/span>\u00a0<\/span><\/p>\n

    List<char> david = [ 'D', 'a', 'v', 'i', 'd' ];<\/code><\/pre>\n
    \u540c\u6837\uff0c\u96c6\u5408\u8868\u8fbe\u5f0f\u4e0d\u80fd\u4e0e<\/span> var <\/span>\u5173\u952e\u5b57\u4e00\u8d77\u4f7f\u7528\u3002<\/span> \u60a8\u5fc5\u987b\u58f0\u660e\u7c7b\u578b\uff0c\u56e0\u4e3a\u96c6\u5408\u8868\u8fbe\u5f0f\u76ee\u524d\u6ca1\u6709\u81ea\u7136\u7c7b\u578b\uff0c\u4ee5\u53ca\u53ef\u4ee5\u8f6c\u6362\u4e3a\u591a\u79cd<\/span>\u96c6\u5408\u7c7b\u578b<\/span><\/a>\u3002 <\/span>\u5bf9<\/span> var <\/span>\u8d4b\u503c\u7684\u652f\u6301\u4ecd\u5728\u8003\u8651\u4e2d\uff0c\u4f46\u56e2\u961f\u5c1a\u672a\u786e\u5b9a\u81ea\u7136\u7c7b\u578b\u5e94\u8be5\u662f\u4ec0\u4e48\u3002<\/span> \u6362\u53e5\u8bdd\u8bf4\uff0c\u5728\u7f16\u5199\u4ee5\u4e0b\u4ee3\u7801\u65f6\uff0c<\/span>C# <\/span>\u7f16\u8bd1\u5668\u4f1a\u51fa\u9519\u5e76\u663e\u793a<\/span> CS9176<\/span>\uff1a\u96c6\u5408\u8868\u8fbe\u5f0f\u6ca1\u6709\u76ee\u6807\u7c7b\u578b<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
    \/\/ Error CS9176: There is no target type for the collection expression\u00a0\r\nvar collection = [1, 2, 3]; <\/code><\/pre>\n
    \u60a8\u53ef\u80fd\u4f1a\u95ee\u81ea\u5df1\uff0c\u201c\u65e2\u7136\u6709\u8fd9\u4e48\u591a\u4e0d\u540c\u7684\u65b9\u6cd5\u6765\u521d\u59cb\u5316\u96c6\u5408\uff0c\u4e3a\u4ec0\u4e48\u6211\u8981\u4f7f\u7528\u65b0\u7684\u96c6\u5408\u8868\u8fbe\u5f0f\u8bed\u6cd5<\/span>\uff1f\u201d <\/span>\u7b54\u6848\u662f\uff0c\u901a\u8fc7\u96c6\u5408\u8868\u8fbe\u5f0f\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528\u76f8\u540c\u7684\u8bed\u6cd5\u4ee5\u4e00\u81f4\u7684\u65b9\u5f0f\u8868\u8fbe\u96c6\u5408\u3002<\/span> \u8fd9\u6709\u52a9\u4e8e\u63d0\u9ad8\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\u548c\u53ef\u7ef4\u62a4\u6027\u3002<\/span> \u6211\u4eec\u5c06\u5728\u63a5\u4e0b\u6765\u7684\u90e8\u5206\u4e2d\u63a2\u8ba8\u66f4\u591a\u4f18\u52bf<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n
    \u96c6\u5408\u8868\u8fbe\u5f0f\u53d8\u5316<\/span><\/b>\ud83c\udfad<\/span><\/b>\u00a0<\/span><\/p>\n
    \u60a8\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\u8868\u793a\u96c6\u5408\u4e3a\u7a7a<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
    int[] emptyCollection = [];\u00a0<\/code><\/pre>\n
    \u7a7a\u96c6\u5408\u8868\u8fbe\u5f0f\u7684\u521d\u59cb\u5316\u662f\u4ee3\u66ff\u4ee5\u524d\u4f7f\u7528\u201c<\/span>new<\/span>\u201d\u5173\u952e\u5b57\u7684\u4ee3\u7801\u7684\u7edd\u4f73\u9009\u62e9\uff0c\u56e0\u4e3a\u5b83\u5df2\u88ab\u7f16\u8bd1\u5668\u4f18\u5316\uff0c\u4ee5\u907f\u514d\u4e3a\u67d0\u4e9b\u96c6\u5408\u7c7b\u578b\u5206\u914d\u5185\u5b58\u3002<\/span> \u4f8b\u5982\uff0c\u5f53\u96c6\u5408\u7c7b\u578b\u662f\u6570\u7ec4<\/span> T[] <\/span>\u65f6\uff0c\u7f16\u8bd1\u5668\u4f1a\u751f\u6210<\/span> Array.Empty<T>()<\/span>\uff0c\u5b83\u6bd4<\/span> new int[] { } <\/span>\u6548\u7387\u66f4\u9ad8\u3002<\/span> \u53e6\u4e00\u79cd\u5feb\u6377\u65b9\u5f0f\u662f\u4f7f\u7528\u96c6\u5408\u8868\u8fbe\u5f0f\u4e2d\u7684\u5143\u7d20\u6570\u91cf\u6765\u8bbe\u7f6e\u96c6\u5408\u5927\u5c0f\uff0c\u4f8b\u5982<\/span> \u5bf9\u4e8e<\/span> List<T> x = [1, 2];<\/span>\u4f7f\u7528<\/span>new List<int>(2)\u3002<\/span>\u00a0<\/span><\/p>\n
    \u96c6\u5408\u8868\u8fbe\u5f0f\u8fd8\u5141\u8bb8\u60a8\u5728\u4e0d\u58f0\u660e\u663e\u5f0f\u7c7b\u578b\u7684\u60c5\u51b5\u4e0b\u8d4b\u503c\u7ed9\u63a5\u53e3\u3002<\/span> \u7f16\u8bd1\u5668\u786e\u5b9a\u7528\u4e8e<\/span> IEnumerable<T>\u3001IReadOnlyList<T> <\/span>\u548c<\/span> IReadOnlyCollection<T> <\/span>\u7b49\u7c7b\u578b\u7684\u7c7b\u578b<\/span>\u3002 <\/span>\u5982\u679c\u5b9e\u9645\u4f7f\u7528\u7684\u7c7b\u578b\u5f88\u91cd\u8981\uff0c\u60a8\u9700\u8981\u58f0\u660e\u5b83\uff0c\u56e0\u4e3a\u5982\u679c\u6709\u66f4\u9ad8\u6548\u7684\u7c7b\u578b\u53ef\u7528\uff0c\u60c5\u51b5\u53ef\u80fd\u4f1a\u53d1\u751f\u53d8\u5316\u3002<\/span> \u540c\u6837\uff0c\u5728\u7f16\u8bd1\u5668\u65e0\u6cd5\u751f\u6210\u66f4\u9ad8\u6548\u7684\u4ee3\u7801\u7684\u60c5\u51b5\u4e0b\uff0c\u4f8b\u5982\u5f53\u96c6\u5408\u7c7b\u578b\u662f<\/span> List<T> <\/span>\u65f6\uff0c\u7f16\u8bd1\u5668\u4f1a\u751f\u6210\u4e00\u4e2a\u65b0\u7684<\/span> List<int>()<\/span>\uff0c\u5b83\u662f\u7b49\u6548\u7684<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n
    \u4f7f\u7528\u7a7a\u96c6\u5408\u8868\u8fbe\u5f0f\u7684\u4f18\u70b9\u6709\u4e09\u4e2a\uff1a<\/span>\u00a0<\/span><\/p>\n