{"id":925,"date":"2020-11-06T15:36:51","date_gmt":"2020-11-06T07:36:51","guid":{"rendered":"http:\/\/www.wangkaixuan.tech\/?p=925"},"modified":"2020-11-06T15:36:51","modified_gmt":"2020-11-06T07:36:51","slug":"%e4%bd%bf%e7%94%a8lambda%e8%a1%a8%e8%be%be%e5%bc%8f%e6%9b%bf%e6%8d%a2%e5%ae%8f%e5%ae%9a%e4%b9%89%e4%bb%a3%e7%a0%81%e6%ae%b5","status":"publish","type":"post","link":"http:\/\/www.wangkaixuan.tech\/?p=925","title":{"rendered":"\u4f7f\u7528lambda\u8868\u8fbe\u5f0f\u66ff\u6362\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">1.\u4ec0\u4e48\u662f\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5<\/h2>\n\n\n\n<p>C\/C++\u5b8f\u5b9a\u4e49\u5c5e\u4e8e\u9884\u5904\u7406\u9636\u6bb5\u7684\u529f\u80fd\uff0c\u64cd\u4f5c\u7684\u5bf9\u8c61\u662f<strong>\u6e90\u4ee3\u7801<\/strong>\u3002\u5728\u9884\u5904\u7406\u9636\u6bb5\uff0c\u7f16\u8bd1\u5668\u6839\u636e\u7528\u6237\u5b9a\u4e49\u7684\u9884\u5904\u7406\u6307\u4ee4\uff0c\u5c06\u6e90\u4ee3\u7801\u6539\u9020\u6210\u53e6\u5916\u4e00\u79cd\u5f62\u5f0f\u3002<\/p>\n\n\n\n<p>\u9700\u8981\u7279\u522b\u6ce8\u610f\u7684\u662f\uff0c\u9884\u5904\u7406\u6307\u4ee4\u867d\u7136\u8ddfC\/C++\u4ee3\u7801\u653e\u5728\u4e00\u4e2a\u6e90\u6587\u4ef6\u91cc\uff0c\u4f46\u5e76\u4e0d\u5c5e\u4e8eC++\u7684\u4e00\u90e8\u5206\uff0c\u56e0\u6b64<strong>\u4e0d\u53d7C++\u8bed\u6cd5\u89c4\u5219\u7684\u7ea6\u675f<\/strong>\u3002\u800c\u8fd9\u4e00\u70b9\uff0c\u6b63\u662f\u6211\u4eec\u4f7f\u7528\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u7684\u6700\u91cd\u8981\u7684\u539f\u56e0\u3002<\/p>\n\n\n\n<p>\u4e0b\u9762\u7684\u4ee3\u7801\u5c55\u793a\u4e86\u4e00\u4e2a\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u7684\u4f8b\u5b50\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/compile with : g++ lambda_test_1.cpp -E -o lambda_test_1_after.cpp\n\n#include &lt;stdio.h>\n\n#define BEFORE_ADD() \\\n    int a, b, c; \\\n    a = 1; \\\n    b = 2\n\n#define AFTER_ADD() \\\n    printf(\"a + b = %d\\n\", c)\n\n\nint main()\n{\n    BEFORE_ADD();\n\n    c = a + b;\n\n    AFTER_ADD();\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u4ee3\u7801\u7b80\u5355\u6613\u61c2\uff0c\u4e0d\u518d\u89e3\u91ca\u3002<\/p>\n\n\n\n<p>\u6211\u4eec\u4f7f\u7528-E\u547d\u4ee4\u7f16\u8bd1\u4e0a\u8ff0\u4ee3\u7801\uff0c\u547d\u4ee4\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>g++ lambda_test_1.cpp -E -o lambda_test_1_after.cpp<\/code><\/pre>\n\n\n\n<p>\u67e5\u770b\u7f16\u8bd1\u540e\u7684\u4ee3\u7801\uff0c\u53d1\u73b0main\u51fd\u6570\u88ab\u66ff\u6362\u6210\u4e86\u5982\u4e0b\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"388\" height=\"203\" src=\"http:\/\/www.wangkaixuan.tech\/wp-content\/uploads\/2020\/11\/image-37.png\" alt=\"\" class=\"wp-image-929\"\/><\/figure>\n\n\n\n<p>\u5b8f\u5b9a\u4e49\u4e2d\u7684\u4ee3\u7801\u88ab\u7b80\u5355\u7c97\u66b4\u5730\u66ff\u6362\u5230\u4e86\u6e90\u6587\u4ef6\u4e2d\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">2.\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u7684\u574f\u5904<\/h2>\n\n\n\n<p>\u5b8f\u5b9a\u4e49\u6700\u5927\u7684\u95ee\u9898\u662f\uff0c\u4f60<strong>\u770b\u5230\u7684\u4ee3\u7801\u548c\u7f16\u8bd1\u5668\u770b\u5230\u7684\u4ee3\u7801\u662f\u4e0d\u540c\u7684<\/strong>\uff0c\u8fd9\u4e2d\u95f4\u6709\u4e00\u4e2a\u9884\u5904\u7406\u5668\u7ffb\u8bd1\u7684\u73af\u8282\uff0c\u518d\u52a0\u4e0a\u5b8f\u5b9a\u4e49\u7684\u4f5c\u7528\u57df\u662f\u5168\u5c40\u7684\uff0c\u6709\u65f6\u5019\u7ffb\u8bd1\u7684\u7ed3\u679c\u53ef\u80fd\u5e76\u4e0d\u5982\u4f60\u6240\u60f3\uff0c\u56e0\u6b64\u4ee3\u7801\u7f16\u8bd1\u6216\u8fd0\u884c\u8d77\u6765\u53ef\u80fd\u4f1a\u6709\u4e00\u4e9b\u5947\u5947\u602a\u602a\u7684\u9519\u8bef\uff0c\u5f88\u96be\u6392\u67e5\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">a) \u4e3e\u4e2a\u4f8b\u5b50<\/h3>\n\n\n\n<p>\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/compile with : g++ -o lambda_test_2 lambda_test_2.cpp\n\n#include &lt;stdio.h>\n\n#define X 2\n#define\tY 3+4\n\nint main()\n{\n    printf(\"X * Y = %d\\n\", X * Y);\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u4f60\u89c9\u5f97\u8fd0\u884c\u7ed3\u679c\u662f\u4ec0\u4e48\uff1f<\/p>\n\n\n\n<p>\u7b54\u6848\u662f10\u800c\u4e0d\u662f24\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"548\" height=\"32\" src=\"http:\/\/www.wangkaixuan.tech\/wp-content\/uploads\/2020\/11\/image-38.png\" alt=\"\" class=\"wp-image-930\"\/><\/figure>\n\n\n\n<p>\u770b\u4e0b\u9884\u5904\u7406\u5668\u7ffb\u8bd1\u7684\u4ee3\u7801\u4f60\u5c31\u4e86\u7136\u4e86\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"388\" height=\"123\" src=\"http:\/\/www.wangkaixuan.tech\/wp-content\/uploads\/2020\/11\/image-39.png\" alt=\"\" class=\"wp-image-931\"\/><\/figure>\n\n\n\n<p>\u9884\u5904\u7406\u5668\u5e76\u6ca1\u6709\u8ba1\u7b973+4\u7684\u7ed3\u679c\u4e0e2\u76f8\u4e58\uff0c\u800c\u662f<strong>\u76f4\u63a5\u628aX\u3001Y\u4ee3\u8868\u7684\u6587\u672c\u8fdb\u884c\u4e86\u66ff\u6362<\/strong>\uff01\u8fd9\u6837\u7684\u8bdd\uff0c\u7531\u4e8e\u4e58\u6cd5\u7684\u4f18\u5148\u7ea7\u6bd4\u8f83\u9ad8\uff0c2\u548c3\u4f1a\u5148\u4e58\uff0c\u7136\u540e\u518d\u548c4\u76f8\u52a0\uff01<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">b) \u518d\u4e3e\u4e2a\u590d\u6742\u70b9\u7684\u4f8b\u5b50<\/h3>\n\n\n\n<p>\u6bd4\u5982\u4e0b\u9762\u4e00\u6bb5\u4ee3\u7801\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"900\" height=\"507\" src=\"http:\/\/www.wangkaixuan.tech\/wp-content\/uploads\/2020\/11\/image-41.png\" alt=\"\" class=\"wp-image-933\"\/><\/figure>\n\n\n\n<p>\u5728\u9605\u8bfb\u7684\u65f6\u5019\u5c31\u6bd4\u8f83\u56f0\u96be\uff0c\u50cfchg_flag\u3001p_old\u3001p_new\u3001p_pkg\u7b49\u90fd\u8981\u4e0e\u5177\u4f53\u7684\u5b8f\u5c55\u5f00\u5904\u7684\u4ee3\u7801\u76f8\u5173\u8054\uff0c\u7a0b\u5e8f\u5458\u9700\u8981\u7528\u4eba\u8111\u5c06\u4e0d\u540c\u7684\u4ee3\u7801\u6bb5\u62fc\u63a5\u8d77\u6765\uff0c\u8017\u8d39\u8111\u529b\u4e0d\u8bf4\uff0c\u8fd8\u5bb9\u6613\u51fa\u9519\u3002<\/p>\n\n\n\n<p>\u8fd9\u6bb5\u4ee3\u7801\u6574\u4f53\u770b\u8d77\u6765\u8fd8\u7b97\u6e05\u6670\uff0c\u5bf9\u4e8e\u4e00\u4e9b\u4e00\u4e9b\u6709\u5d4c\u5957\u7684\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u6765\u8bb2\uff0c\u4eba\u8111\u62fc\u63a5\u7684\u65f6\u5019\u4f1a\u66f4\u56f0\u96be\uff0c\u57fa\u672c\u4e0a\u4ee3\u7801\u8dd1\u901a\u540e\u5c31\u6ca1\u4eba\u6562\u52a8\u4e86\u3002\u6240\u4ee5\u4e3a\u4e86\u5c11\u6328\u9a82\uff0c\u8fd8\u662f\u4e0d\u8981\u5199\u8fd9\u4e48\u53d8\u6001\u7684\u4ee3\u7801\u4e86\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">3.\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u7684\u597d\u5904<\/h2>\n\n\n\n<p>\u5b8f\u5b9a\u4e49\u4e5f\u4e0d\u662f\u4e00\u65e0\u662f\u5904\uff0c\u5982\u679c\u81ea\u8eab\u7684\u80fd\u529b\u8db3\u591f\u9a7e\u9a6d\u5b8f\u5b9a\u4e49\u53ef\u80fd\u5e26\u6765\u7684\u5751\uff0c\u5e76\u4e14\u4e25\u683c\u63a7\u5236\u5b8f\u5b9a\u4e49\u7684\u4f7f\u7528\u573a\u666f\u4ee5\u53ca\u4ee3\u7801\u89c4\u6a21\u7684\u8bdd\uff0c\u8fd8\u662f\u80fd\u5e26\u6765\u8fd0\u884c\u6548\u7387\u548c\u53ef\u8bfb\u6027\u7684\u53cc\u91cd\u63d0\u5347\u7684\u3002<\/p>\n\n\n\n<p>\u8bf4<strong>\u63d0\u9ad8\u8fd0\u884c\u6548\u7387<\/strong>\uff0c\u5176\u5b9e\u662f\u4f7f\u7528\u5b8f\u5b9a\u4e49\u4ee3\u66ff\u51fd\u6570\uff0c\u53ef\u4ee5\u907f\u514d\u8c03\u7528\u51fd\u6570\u65f6\u4fdd\u5b58\u548c\u6062\u590d\u73b0\u573a\u7684\u5f00\u9500\u3002\u8fd9\u4e00\u70b9\u5728C\u8bed\u8a00\u65f6\u4ee3\u662f\u6bd4\u8f83\u91cd\u8981\u7684\uff0c\u4f46\u662f\u5728C++\u65f6\u4ee3\uff0c\u5176\u6548\u7387\u63d0\u5347\u7684\u529f\u80fd\u53ef\u7531\u5185\u8054\u51fd\u6570\u4ee3\u66ff\uff0c\u53ef\u8bfb\u6027\u5927\u5927\u63d0\u9ad8\uff0c\u800c\u6027\u80fd\u53c8\u57fa\u672c\u65e0\u635f\u5931\u3002<\/p>\n\n\n\n<p>\u8bf4<strong>\u63d0\u9ad8\u53ef\u8bfb\u6027<\/strong>\uff0c\u5176\u5b9e\u662f\u628a\u4e00\u4e9b\u7b80\u5355\u5230\u6ca1\u5fc5\u8981\u5199\u6210\u51fd\u6570\u7684\u529f\u80fd\u7528\u5b8f\u5b9a\u4e49\u4ee3\u66ff\u4e86\uff0c\u4ee5\u51cf\u5c11\u4ee3\u7801\u957f\u5ea6\u3002\u6bd4\u5982\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"676\" height=\"47\" src=\"http:\/\/www.wangkaixuan.tech\/wp-content\/uploads\/2020\/11\/image-42.png\" alt=\"\" class=\"wp-image-934\"\/><\/figure>\n\n\n\n<p>\u4f46\u662f\u50cf\u8fd9\u79cd\u529f\u80fd\u5728\u73b0\u4ee3C++\u4e2d\u6709\u66f4\u597d\u7684\u89e3\u51b3\u65b9\u6cd5\uff0c\u90a3\u5c31\u662flambda\u8868\u8fbe\u5f0f\uff0c\u8fd9\u4e00\u70b9\u6211\u4eec\u7a0d\u540e\u8ba8\u8bba\u3002<\/p>\n\n\n\n<p>\u5b8f\u5b9a\u4e49\u56e0\u5176\u5a01\u529b\u5f3a\u5927\uff0c\u53ef\u4ee5\u7a81\u7834\u8bed\u8a00\u7684\u8bed\u6cd5\u9650\u5236\uff0c\u7528\u7684\u597d\u4e86\u786e\u5b9e\u80fd\u591f\u8fbe\u5230\u51fa\u795e\u5165\u5316\u7684\u6548\u679c\uff0c\u4f46\u662f\u9700\u8981\u76f8\u5f53\u7684\u529f\u529b\u624d\u884c\u3002\u636e\u6211\u6240\u77e5\uff0c\u5728\u5f00\u6e90\u9886\u57df\u8fd8\u662f\u6709\u4e0d\u5c11\u8fd9\u79cd\u4f8b\u5b50\u7684\u3002<\/p>\n\n\n\n<p>\u6bd4\u5982linux\u5185\u6838\u4e2d\u5bf9list\u6570\u636e\u7ed3\u6784\u7684\u64cd\u4f5c\u5c31\u4f7f\u7528\u4e86\u5927\u91cf\u7684\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\uff08<a href=\"https:\/\/github.com\/torvalds\/linux\/blob\/master\/include\/linux\/list.h\">\u94fe\u63a5\u5728\u6b64<\/a>\uff09\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/**\n * list_for_each_entry\t-\titerate over list of given type\n * @pos:\tthe type * to use as a loop cursor.\n * @head:\tthe head for your list.\n * @member:\tthe name of the list_head within the struct.\n *\/\n#define list_for_each_entry(pos, head, member)\t\t\t\t\\\n\tfor (pos = list_first_entry(head, typeof(*pos), member);\t\\\n\t     !list_entry_is_head(pos, head, member);\t\t\t\\\n\t     pos = list_next_entry(pos, member))\n\n\/**\n * list_for_each_entry_reverse - iterate backwards over list of given type.\n * @pos:\tthe type * to use as a loop cursor.\n * @head:\tthe head for your list.\n * @member:\tthe name of the list_head within the struct.\n *\/\n#define list_for_each_entry_reverse(pos, head, member)\t\t\t\\\n\tfor (pos = list_last_entry(head, typeof(*pos), member);\t\t\\\n\t     !list_entry_is_head(pos, head, member); \t\t\t\\\n\t     pos = list_prev_entry(pos, member))<\/code><\/pre>\n\n\n\n<p>\u6bd4\u5982\u8c37\u6b4c\u7684gtest\u5355\u5143\u6d4b\u8bd5\u6846\u67b6\u4e5f\u4f7f\u7528\u4e86\u5927\u91cf\u7684\u5b8f\u5b9a\u4e49\uff0c\u4f7f\u5f97\u6700\u7ec8\u7528\u6237\u53ef\u4ee5\u7528\u5f88\u7b80\u6d01\u7684\u5f62\u5f0f\u7f16\u5199\u5355\u5143\u6d4b\u8bd5\u4ee3\u7801\uff08<a href=\"https:\/\/github.com\/google\/googletest\/blob\/master\/googletest\/include\/gtest\/gtest.h\">\u94fe\u63a5\u5728\u6b64<\/a>\uff09\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#define EXPECT_TRUE(condition) \\\n  GTEST_TEST_BOOLEAN_(condition, #condition, false, true, \\\n                      GTEST_NONFATAL_FAILURE_)\n#define EXPECT_FALSE(condition) \\\n  GTEST_TEST_BOOLEAN_(!(condition), #condition, true, false, \\\n                      GTEST_NONFATAL_FAILURE_)\n#define ASSERT_TRUE(condition) \\\n  GTEST_TEST_BOOLEAN_(condition, #condition, false, true, \\\n                      GTEST_FATAL_FAILURE_)\n#define ASSERT_FALSE(condition) \\\n  GTEST_TEST_BOOLEAN_(!(condition), #condition, true, false, \\\n                      GTEST_FATAL_FAILURE_)<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">4.lambda\u8868\u8fbe\u5f0f\u7684\u6838\u5fc3\u7279\u6027<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">a) \u6838\u5fc3\u7279\u6027\u5feb\u901f\u56de\u987e<\/h3>\n\n\n\n<p>C++11\u6807\u51c6\u5f15\u5165\u4e86lambda\u8868\u8fbe\u5f0f\u7279\u6027\uff0c\u4f7f\u5f97C++\u5f80\u73b0\u4ee3\u8bed\u8a00\u53c8\u524d\u8fdb\u4e86\u4e00\u5927\u6b65\u3002<\/p>\n\n\n\n<p>lambda\u8868\u8fbe\u5f0f\u662f\u4e00\u79cd\u53ef\u8c03\u7528\u5bf9\u8c61\uff0c\u5728C\u8bed\u8a00\u65f6\u4ee3\uff0c\u53ef\u8c03\u7528\u5bf9\u8c61\u53ea\u6709\u51fd\u6570\u548c\u51fd\u6570\u6307\u9488\u4e24\u79cd\uff0cC++11\u4e4b\u524d\uff0c\u91cd\u8f7d\u4e86\u51fd\u6570\u8c03\u7528\u8fd0\u7b97\u7b26\u7684\u7c7b\u5bf9\u8c61\u4e5f\u7b97\u662f\u53ef\u8c03\u7528\u5bf9\u8c61\u7684\u4e00\u79cd\u3002<\/p>\n\n\n\n<p>\u6211\u4eec\u53ef\u4ee5\u5c06lambda\u8868\u8fbe\u5f0f\u7406\u89e3\u4e3a\u4e00\u4e2a\u672a\u547d\u540d\u7684\u5185\u8054\u51fd\u6570\u3002\u4e0e\u4efb\u4f55\u51fd\u6570\u7c7b\u4f3c\uff0c\u4e00\u4e2alambda\u8868\u8fbe\u5f0f\u5177\u6709\u4e00\u4e2a\u8fd4\u56de\u7c7b\u578b\u3001\u4e00\u4e2a\u53c2\u6570\u5217\u8868\u548c\u4e00\u4e2a\u51fd\u6570\u4f53\uff1a<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>[capture list] (parameter list) -&gt; return type { function body }<\/p><\/blockquote>\n\n\n\n<p>\u5176\u4e2d\uff0c\u6355\u83b7\u5217\u8868(capture list)\u662f\u4e00\u4e2alambda\u8868\u8fbe\u5f0f<strong>\u6240\u5728\u51fd\u6570<\/strong>\u4e2d\u5b9a\u4e49\u7684<strong>\u5c40\u90e8\u53d8\u91cf<\/strong>\u7684\u5217\u8868\u3002\u8fd4\u56de\u7c7b\u578b\u3001\u53c2\u6570\u5217\u8868\u548c\u51fd\u6570\u4f53\u90fd\u4e0e\u666e\u901a\u51fd\u6570\u65e0\u5f02\u3002<\/p>\n\n\n\n<p>\u5982\u65e0\u5fc5\u8981\uff0clambda\u8868\u8fbe\u5f0f\u53ef\u4ee5\u7701\u7565\u53c2\u6570\u5217\u8868\u548c\u8fd4\u56de\u7c7b\u578b\u4e0d\u5199\uff0c\u4f46\u6355\u83b7\u5217\u8868\u548c\u51fd\u6570\u4f53\u5fc5\u987b\u5305\u542b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>auto lambda_fucn = &#91;] { return 2*3; }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">b) lambda\u8868\u8fbe\u5f0f\u600e\u4e48\u7528<\/h3>\n\n\n\n<p>lambda\u8868\u8fbe\u5f0f<strong>\u5b9a\u4e49\u5728\u51fd\u6570\u5185<\/strong>\uff0c\u6355\u83b7\u7684\u4e5f\u662f<strong>\u51fd\u6570\u7684\u5c40\u90e8\u53d8\u91cf<\/strong>\uff0c\u8fd9\u4e00\u7279\u6027\u51b3\u5b9a\u4e86lambda\u8868\u8fbe\u5f0f\u975e\u5e38\u9002\u5408\u5c01\u88c5\u90a3\u4e9b<strong>\u51fd\u6570\u4f53\u5185<\/strong>\u8f83\u4e3a\u7e41\u7410\u7684\u3001\u91cd\u590d\u51fa\u73b0\u7684\u4ee3\u7801\u6bb5\u3002<\/p>\n\n\n\n<p>lambda\u8868\u8fbe\u5f0f\u81ea\u52a8\u6355\u83b7\u5c40\u90e8\u53d8\u91cf\u7684\u7279\u6027\uff0c\u4f7f\u5f97\u4e0d\u7528\u7f16\u5199\u957f\u957f\u7684\u53c2\u6570\u5217\u8868\u5373\u53ef\u4f7f\u7528\u4e00\u4e9b\u53d8\u91cf\uff0c\u4ee3\u7801\u4f1a\u56e0\u6b64\u53d8\u5f97\u7b80\u6d01\u6e05\u6670\uff0c\u8fd9\u4e00\u70b9\u662f\u51fd\u6570\u6bd4\u4e0d\u4e86\u7684\u3002<\/p>\n\n\n\n<p>lambda\u8868\u8fbe\u5f0f\u5e76\u4e0d\u662f\u6765\u66ff\u4ee3\u51fd\u6570\u7684\uff0c\u4ed6\u5176\u5b9e\u662f\u51fd\u6570\u7684\u4e00\u79cd<strong>\u8865\u5145<\/strong>\uff0c\u4e00\u4e9b\u8f83\u4e3a\u7b80\u5355\u7684\uff0c\u91cd\u590d\u51fa\u73b0\u7684\uff0c<strong>\u5c40\u90e8\u6027<\/strong>\u7684\u903b\u8f91\uff0c\u53ef\u4ee5\u4f7f\u7528lambda\u8868\u8fbe\u5f0f\u5b9e\u73b0\uff0c\u4f46\u8f83\u4e3a\u590d\u6742\u7684\uff0c\u9700\u8981\u5728\u8f83\u5927\u8303\u56f4\u5185\u91cd\u7528\u7684\u903b\u8f91\uff0c\u8fd8\u5f97\u7528\u51fd\u6570\u5b9e\u73b0\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">5.\u4f7f\u7528\u6837\u4f8b<\/h2>\n\n\n\n<p>\u5728\u5b9e\u9645\u7684\u8f6f\u4ef6\u5f00\u53d1\u8fc7\u7a0b\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\uff0c\u5f80\u5f80\u662f\u7528\u51fd\u6570\u5b9e\u73b0\u4e0d\u4e86\uff0c\u6216\u8005\u4e0d\u591f\u7ecf\u6d4e\u3002<\/p>\n\n\n\n<p>\u5b8f\u5b9a\u4e49\u7a81\u7834\u8bed\u6cd5\u9650\u5236\u5bf9\u6e90\u4ee3\u7801\u8fdb\u884c\u6587\u672c\u66ff\u6362\u7684\u529f\u80fd\uff0c\u522b\u8bf4\u51fd\u6570\uff0c\u5c31\u662flambda\u8868\u8fbe\u5f0f\u4e5f\u66ff\u4ee3\u4e0d\u4e86\uff0c\u56e0\u6b64\u8fd9\u90e8\u5206\u529f\u80fd\u8be5\u7528\u8fd8\u5f97\u7528\uff08\u4f46\u662f\u9664\u975e\u975e\u5e38\u6709\u5fc5\u8981\uff0c\u5c3d\u91cf\u4e0d\u8981\u7528\uff09\u3002<\/p>\n\n\n\n<p>\u4f46\u662f\u5bf9\u4e8e\u53e6\u4e00\u79cd\u60c5\u51b5\uff0c\u5373\u7528\u51fd\u6570\u5b9e\u73b0\u4e0d\u591f\u7ecf\u6d4e\u7684\u60c5\u51b5\uff0c\u7528lambda\u8868\u8fbe\u5f0f\u5f80\u5f80\u80fd\u5b8c\u7f8e\u89e3\u51b3\u3002<\/p>\n\n\n\n<p>\u4e0b\u9762\u4e3e\u51e0\u4e2a\u4f8b\u5b50\uff1a<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">a\uff09\u51fd\u6570\u6bd4\u53c2\u6570\u5217\u8868\u8fd8\u957f<\/h3>\n\n\n\n<p>\u6bd4\u5982\u50cf\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/compile with : g++ -o lambda_test_4 lambda_test_4.cpp -std=c++11\n\n#include &lt;stdio.h>\n\nstruct counter_t\n{\n    int val;\n};\n\nint sum_counter(counter_t &amp;a, counter_t &amp;b, counter_t &amp;c, int multply_d)\n{\n    return (a.val + b.val + c.val) * multply_d;\n}\n\nint main()\n{\n    counter_t a, b, c;\n    a.val = b.val = c.val = 1;\n\n    printf(\"sum = %d\\n\", sum_counter(a , b, c, 2));\n\n    auto lambda_sum_cnter = &#91;&amp;a, &amp;b, &amp;c](int multply_d)->int\n        {\n            return (a.val + b.val + c.val) * multply_d;\n        };\n\n    printf(\"sum = %d\\n\", lambda_sum_cnter(2));\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u50cf\u4e0a\u8ff0\u8fd9\u79cd\u6781\u5176\u7b80\u5355\u7684\u903b\u8f91\uff0c\u5982\u679c\u7528\u51fd\u6570\u5199\u8d77\u6765\uff0c\u53c2\u6570\u5217\u8868\u6bd4\u529f\u80fd\u903b\u8f91\u8fd8\u957f\uff0c\u7528\u51fd\u6570\u5199\u663e\u7136\u4e0d\u592a\u7ecf\u6d4e\u3002<\/p>\n\n\n\n<p>\u800c\u5229\u7528lambda\u8868\u8fbe\u5f0f\u81ea\u52a8\u6355\u83b7\u5c40\u90e8\u53d8\u91cf\u7684\u529f\u80fd\uff0c\u6211\u4eec\u8ba9\u4ed6\u81ea\u52a8\u6355\u83b7a\u3001b\u3001c\u4e09\u4e2a\u53d8\u91cf\uff0c\u8fd9\u6837\u6211\u4eec\u53ea\u9700\u8981\u4f20\u9012\u4e00\u4e2a\u53c2\u6570multiply_d\u5373\u53ef\uff0c\u770b\u8d77\u6765\u7b80\u6d01\u4e86\u5f88\u591a\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">b) \u5c40\u90e8\u6027\u7684\u91cd\u590d\u903b\u8f91<\/h3>\n\n\n\n<p>\u770b\u4e0b\u9762\u8fd9\u4e2a\u4f8b\u5b50\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/compile with : g++ -o lambda_test_5 lambda_test_5.cpp -std=c++11\n\n#include &lt;stdio.h>\n\n#define FID_A       15\n#define FID_B       6\n#define FID_C       88\n#define FID_D       23\n#define FID_E       121\n\nstruct buffer_t\n{\n    int val_vec&#91;5];\n};\n\nvoid copy_buf(buffer_t &amp;buf_x, buffer_t &amp;buf_y)\n{\n    if(buf_x.val_vec&#91;0] != buf_y.val_vec&#91;0])\n    {\n        \/\/p_pkg->SetVal(buf_y.val_vec&#91;0], FID_A);\n        buf_x.val_vec&#91;0] = buf_y.val_vec&#91;0];\n    }\n    if(buf_x.val_vec&#91;1] != buf_y.val_vec&#91;1])\n    {\n        \/\/p_pkg->SetVal(buf_y.val_vec&#91;1], FID_B);\n        buf_x.val_vec&#91;1] = buf_y.val_vec&#91;1];\n    }\n    if(buf_x.val_vec&#91;2] != buf_y.val_vec&#91;2])\n    {\n        \/\/p_pkg->SetVal(buf_y.val_vec&#91;2], FID_C);\n        buf_x.val_vec&#91;2] = buf_y.val_vec&#91;2];\n    }\n    if(buf_x.val_vec&#91;3] != buf_y.val_vec&#91;3])\n    {\n        \/\/p_pkg->SetVal(buf_y.val_vec&#91;3], FID_D);\n        buf_x.val_vec&#91;3] = buf_y.val_vec&#91;3];\n    }\n    if(buf_x.val_vec&#91;4] != buf_y.val_vec&#91;4])\n    {\n        \/\/p_pkg->SetVal(buf_y.val_vec&#91;4], FID_E);\n        buf_x.val_vec&#91;4] = buf_y.val_vec&#91;4];\n    }\n}\n\nvoid copy_buf_by_lambda(buffer_t &amp;buf_x, buffer_t &amp;buf_y)\n{\n    auto lambda_cpy_buf = &#91;&amp;buf_x, &amp;buf_y](int idx, int fid)\n        {\n            if(buf_x.val_vec&#91;idx] != buf_y.val_vec&#91;idx])\n            {\n                \/\/p_pkg->SetVal(buf_y.val_vec&#91;idx], fid);\n                buf_x.val_vec&#91;idx] = buf_y.val_vec&#91;idx];\n            }\n        };\n    \n    lambda_cpy_buf(0, FID_A);\n    lambda_cpy_buf(1, FID_B);\n    lambda_cpy_buf(2, FID_C);\n    lambda_cpy_buf(3, FID_D);\n    lambda_cpy_buf(4, FID_E);\n}\n\nint main()\n{\n\n    buffer_t buf_x, buf_y;\n\n    \/\/copy_buf(buf_x, buf_y);\n    copy_buf_by_lambda(buf_x, buf_y);\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u6211\u4eec\u7684\u51fd\u6570\u9700\u8981\u505a\u4e00\u4ef6\u4e8b\u60c5\uff0c\u5373\u68c0\u67e5buf_y\u7684\u4e94\u4e2a\u5b57\u6bb5\u76f8\u5bf9\u4e8ebuf_x\u662f\u5426\u6709\u53d8\u5316\uff0c\u5982\u679c\u6709\u53d8\u5316\uff0c\u628a\u53d8\u5316\u7684\u5b57\u6bb5\u586b\u5199\u5230\u6570\u636e\u5305\u4e2d\u53d1\u51fa\u53bb\u3002<\/p>\n\n\n\n<p>\u6211\u4eec\u63d0\u4f9b\u4e86\u4e24\u4e2a\u7248\u672c\u7684\u5b9e\u73b0\uff0c\u4e00\u4e2a\u662f\u7528\u666e\u901a\u51fd\u6570\uff08\u6ce8\u610f\u4e94\u4e2aFID\u662f\u6ca1\u6709\u89c4\u5f8b\u7684\uff0c\u56e0\u6b64\u4e0d\u80fd\u7528\u5faa\u73af\uff09\uff0c\u91cc\u9762\u5305\u542b\u4e86\u5927\u91cf\u7684\u91cd\u590d\u5224\u65ad\uff0c\u4f46\u662f\u53c8\u4e0d\u80fd\u7528\u5faa\u73af\u5b9e\u73b0\u3002\u4e00\u4e2a\u662f\u7528lambda\u8868\u8fbe\u5f0f\uff0c\u6355\u83b7\u51fd\u6570\u5185\u7684buf_x\u548cbuf_y\u53d8\u91cf\uff0c\u7f29\u51cf\u4e86\u53c2\u6570\u5217\u8868\uff0c\u540c\u65f6\u53c8\u6d88\u9664\u4e86\u91cd\u590d\u90e8\u5206\uff0c\u770b\u8d77\u6765\u975e\u5e38\u7b80\u6d01\u3002<\/p>\n\n\n\n<p>\u8fd9\u4e2a\u573a\u666f\u7684\u5173\u952e\u662f\uff0c<strong>\u5c40\u90e8<\/strong>\u548c<strong>\u91cd\u590d<\/strong>\u3002\u5982\u679c\u903b\u8f91\u5177\u6709\u5168\u5c40\u6027\uff0c\u90a3\u4e48\u5c3d\u91cf\u7528\u51fd\u6570\uff1b\u5982\u679c\u903b\u8f91\u4e0d\u5177\u5907\u91cd\u590d\u6027\uff0c\u90a3\u4e48\u8fd8\u4e0d\u5982\u5c06\u5927\u51fd\u6570\u62c6\u89e3\u6210\u5c0f\u51fd\u6570\uff0c\u7528lambda\u8868\u8fbe\u5f0f\u53cd\u800c\u6709\u70b9\u5f97\u4e0d\u507f\u5931\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">c) \u9ad8\u7ea7\u7528\u6cd5\uff1a\u62d3\u5c55\u4f5c\u7528\u57df<\/h3>\n\n\n\n<p>\u5728\u4e0a\u9762\u7684\u6587\u672c\u4e2d\uff0c\u6211\u4eec\u591a\u6b21\u7528\u52a0\u7c97\u7684\u9ed1\u4f53\u5b57\u63d0\u9192\u60a8\uff0clambda\u51fd\u6570\u662f\u5c40\u90e8\u7684\uff0c\u53ea\u80fd\u6355\u83b7\u51fd\u6570\u7684\u5c40\u90e8\u53d8\u91cf\u3002\u5230\u90a3\u65f6\u5176\u5b9e\u6211\u4eec\u53ef\u4ee5\u5229\u7528\u4e00\u4e2a\u5c0f\u6280\u5de7\uff0c\u5b9e\u73b0\u5c06lambda\u8868\u8fbe\u5f0f\u7684\u4f5c\u7528\u57df\u62d3\u5c55\u5230\u51fd\u6570\u5916\u9762\u3002<\/p>\n\n\n\n<p>\u6211\u4eec\u5c06\u4e0a\u9762\u7684\u4f8b\u5b50\u7a0d\u52a0\u6539\u9020\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/compile with : g++ -o lambda_test_6 lambda_test_6.cpp -std=c++11\n\n#include &lt;stdio.h>\n#include &lt;functional>\n\n#define FID_A       15\n#define FID_B       6\n#define FID_C       88\n#define FID_D       23\n#define FID_E       121\n\nstruct buffer_t\n{\n    int val_vec&#91;5];\n};\n\ntypedef std::function&lt;void(int idx, int fid)> copy_func_t;\n\nvoid copy_levels(copy_func_t cp_func)\n{\n    cp_func(0, FID_A);\n    cp_func(1, FID_B);\n    cp_func(2, FID_C);\n    cp_func(3, FID_D);\n    cp_func(4, FID_E);\n}\n\nvoid copy_buf_by_lambda(buffer_t &amp;buf_x, buffer_t &amp;buf_y)\n{\n    auto lambda_cpy_buf = &#91;&amp;buf_x, &amp;buf_y](int idx, int fid)\n        {\n            if(buf_x.val_vec&#91;idx] != buf_y.val_vec&#91;idx])\n            {\n                \/\/p_pkg->SetVal(buf_y.val_vec&#91;idx], fid);\n                buf_x.val_vec&#91;idx] = buf_y.val_vec&#91;idx];\n            }\n        };\n\n    copy_levels(lambda_cpy_buf);\n}\n\nint main()\n{\n\n    buffer_t buf_x, buf_y;\n\n    \/\/copy_buf(buf_x, buf_y);\n    copy_buf_by_lambda(buf_x, buf_y);\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u8981\u70b9\u5982\u4e0b\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u6211\u4eec\u7528std::function\u5b9a\u4e49\u4e86\u4e00\u4e2a\u4e0elambda\u8868\u8fbe\u5f0f<strong>\u53c2\u6570\u5217\u8868<\/strong>\u76f8\u540c\u7684function\u7c7b\u578b\uff08\u6ce8\u610f\u8fd9\u91cc\u6ca1\u6709\u6807\u660e\u6355\u83b7\u7684\u4e24\u4e2a\u53d8\u91cf\uff09<\/li><li>\u6211\u4eec\u518d\u5b9a\u4e49\u4e00\u4e2a\u51fd\u6570\uff0c\u53c2\u6570\u662f\u4e0a\u9762\u5b9a\u4e49\u7684funciton\u7c7b\u578b\uff0c\u5185\u90e8\u76f4\u63a5\u8c03\u7528\u53c2\u6570\u4e2d\u7684function(\u6ce8\u610f\u8fd9\u4e2a\u51fd\u6570\u4e2d\u5e76\u6ca1\u6709\u770b\u5230lambda\u8868\u8fbe\u5f0f\u6355\u83b7\u7684\u4e24\u4e2a\u53d8\u91cf\uff09<\/li><li>\u5728\u539f\u5148\u7684\u51fd\u6570\u4e2d\uff0c\u6211\u4eec\u53ea\u5b9a\u4e49lambda\u8868\u8fbe\u5f0f\uff0c\u628a\u5b9a\u4e49\u7684\u7ed3\u679c\u4f20\u9012\u7ed9\u53e6\u5916\u7684\u51fd\u6570\u53bb\u8c03\u7528<\/li><\/ul>\n\n\n\n<p>\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0clambda\u6355\u83b7\u7684\u53d8\u91cf\u5728\u5b9a\u4e49lambda\u8868\u8fbe\u5f0f\u7684\u51fd\u6570\u4e2d\u5b9a\u4e49\uff0c\u4f46\u5b9e\u9645\u7684\u4f7f\u7528\u786e\u662f\u5728\u53e6\u5916\u7684\u51fd\u6570\u4e2d\u3002\u76f8\u5f53\u4e8e\u62d3\u5c55\u4e86lambda\u8868\u8fbe\u5f0f\u7684\u4f5c\u7528\u8303\u56f4\u3002<\/p>\n\n\n\n<p>\u8fd9\u6837\u6709\u4ec0\u4e48\u597d\u5904\u5462\uff1f<\/p>\n\n\n\n<p>\u5229\u7528\u8fd9\u4e2a\u7279\u6027\uff0c\u6211\u4eec\u53ef\u4ee5\u628a\u903b\u8f91\u7684\u5b9e\u73b0\u96c6\u4e2d\u8d77\u6765\uff0c\u5e76\u4e14\u5c06\u903b\u8f91\u7684\u5b9e\u73b0\u4e0e\u8c03\u7528\u5206\u5f00\u3002<\/p>\n\n\n\n<p>\u5bf9\u4e8e\u4e00\u4e9b\u8f83\u4e3a\u901a\u7528\u7684\u64cd\u4f5c\uff0c\u6211\u4eec\u53ef\u4ee5\u5b9a\u4e49\u4e00\u4e2a\u5165\u53e3\u51fd\u6570\uff0c\u628a\u5b9e\u73b0\u4ee5lambda\u8868\u8fbe\u5f0f\u7684\u5f62\u5f0f\u96c6\u4e2d\u5199\u5728\u5165\u53e3\u51fd\u6570\u4e2d\uff0c\u8fd9\u6837\u65b9\u4fbf\u5c06\u6765\u7ef4\u62a4\uff1b\u76f8\u5173\u53d8\u91cf\u5219\u7edf\u4e00\u4f20\u7ed9\u5165\u53e3\u51fd\u6570\uff0c\u7531lambda\u8868\u8fbe\u5f0f\u6355\u83b7\uff0c\u8fd9\u6837\u5165\u53e3\u51fd\u6570\u8c03\u7528\u4e0b\u7ea7\u51fd\u6570\u7684\u65f6\u5019\u5c31\u4e0d\u7528\u5199\u957f\u957f\u7684\u53c2\u6570\u5217\u8868\u4e86\uff1b\u6700\u540e\u5165\u53e3\u51fd\u6570\u5c06\u8fd9\u4e9blambda\u8868\u8fbe\u5f0f\u901a\u8fc7\u53c2\u6570\u7684\u5f62\u5f0f\u4f20\u9012\u7ed9\u4e0b\u7ea7\u51fd\u6570\uff0c\u7531\u4ed6\u4eec\u8fdb\u884c\u903b\u8f91\u7684\u8c03\u7528\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">6.\u5e76\u975e\u4e07\u80fd<\/h2>\n\n\n\n<p>lambda\u8868\u8fbe\u5f0f\u5e76\u975e\u4e07\u80fd\u7684\uff0c\u81f3\u5c11\u5728\u4ee5\u4e0b\u4e24\u70b9\u4e0a\uff0clambda\u8868\u8fbe\u5f0f\u5c1a\u4e0d\u80fd\u53d6\u4ee3\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">a) \u4e0d\u652f\u6301\u6cdb\u578b<\/h3>\n\n\n\n<p>\u5728\u524d\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u5b9a\u7684\u573a\u666f\u6bd4\u8f83\u7406\u60f3\uff0cbuffer_t\u7684\u6240\u6709\u7684\u53c2\u6570\u90fd\u662fint\u7c7b\u578b\u7684\u3002\u800c\u5982\u679c\u5b9e\u9645\u7684\u5f00\u53d1\u5de5\u4f5c\u4e2d\uff0c\u91cd\u590d\u4ee3\u7801\u5b58\u5728\uff0c\u4f46\u53c2\u6570\u4e0d\u540c\uff0c\u90a3\u6211\u4eec\u5c31\u9700\u8981\u4e3a\u6bcf\u5957\u53c2\u6570\u90fd\u5199\u4e00\u5957lambda\u8868\u8fbe\u5f0f\uff0c\u867d\u7136\u4ed6\u4eec\u7684\u51fd\u6570\u4f53\u4e00\u6a21\u4e00\u6837\u3002<\/p>\n\n\n\n<p>\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0clambda\u8868\u8fbe\u5f0f\u6d88\u9664\u91cd\u590d\u4ee3\u7801\u7684\u529f\u80fd\u5c31\u5927\u5927\u524a\u5f31\u4e86\u3002<\/p>\n\n\n\n<p>\u597d\u5728C++20\u6807\u51c6\u4e2d\u9884\u8ba1\u52a0\u5165\u6cdb\u578b\u652f\u6301\uff0c\u8ba9\u6211\u4eec\u671f\u5f85\u5427~~<\/p>\n\n\n\n<p>\u800c\u5b8f\u5b9a\u4e49\u5219\u5b8c\u5168\u4e0d\u53d7\u9650\u5236\uff0c\u56e0\u4e3a\u5bf9\u5b8f\u5b9a\u4e49\u6765\u8bb2\uff0c\u5c31\u6ca1\u6709\u7c7b\u578b\u53ef\u8a00\uff0c\u4f55\u6765\u6cdb\u578b\u4e4b\u8bf4\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#define COPY_FIELD(OLD_VAL, NEW_VAL, FID) \\\n    if(OLD_VAL != NEW_VAL) \\\n    { \\\n        p_pkg->SetVal(NEW_VAL, FID); \\\n        OLD_VAL = NEW_VAL; \\\n    }<\/code><\/pre>\n\n\n\n<p>\u6bd4\u5982\u4e0a\u9762\u8fd9\u6bb5\u4ee3\u7801\u5c31\u53ef\u4ee5\u9002\u914dN\u591a\u79cd\u7c7b\u578b\uff0c\u6d88\u9664\u91cd\u590d\u4ee3\u7801\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">b) \u4e0d\u80fd\u7a81\u7834\u8bed\u8a00\u8bed\u6cd5\u9650\u5236<\/h3>\n\n\n\n<p>\u4e3e\u4e00\u4e2a\u7b80\u5355\u7684\u573a\u666f\uff0c\u5047\u8bbe\u6211\u4eec\u8981\u64cd\u4f5c\u7684\u662f\u4e24\u4e2a\u7ed3\u6784\u4f53\u7684\u540c\u540d\u53c2\u6570\uff0c\u7528\u5b8f\u5b9a\u4e49\u5c31\u53ef\u4ee5\u7b80\u5355\u7684\u5199\u6210\u4e0b\u9762\u8fd9\u79cd\u5f62\u5f0f\uff0c\u5f88\u7b80\u6d01\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#define COPY_FIELD(FLD_NAME, FID) \\\n    if(old_buf.FLD_NAME != new_buf.FLD_NAME) \\\n    { \\\n        p_pkg->SetVal(new_buf.FLD_NAME, FID); \\\n        old_buf.FLD_NAME = new_buf.FLD_NAME; \\\n    }\n\n\/\/\u8c03\u7528\nCOPY_FIELD(fld_a, FID_A);<\/code><\/pre>\n\n\n\n<p>\u56e0\u4e3a\u5b8f\u5b9a\u4e49\u662f\u7b80\u5355\u7684\u6587\u672c\u66ff\u6362\uff0c\u5728\u4f60\u4f20\u5165\u5b57\u6bb5\u540d\u79f0\u7684\u65f6\u5019\uff0c\u4ed6\u4f1a\u628a\u4e0b\u9762\u7684\u201c\u5bf9\u8c61\u540d.\u5b57\u6bb5\u540d\u201d\u8865\u5168\uff0c\u5f62\u6210\u4e00\u6bb5\u5b8c\u6574\u7684\u4ee3\u7801\u3002\u800clambda\u8868\u8fbe\u5f0f\u5c31\u4e0d\u884c\uff0c\u5fc5\u987b\u76f4\u63a5\u5b8c\u6574\u7684\u5199\u51fa\u201c\u5bf9\u8c61\u540d.\u5b57\u6bb5\u540d\u201d\uff0c\u793a\u4f8b\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>auto lambda_cpy_fld = &#91;](int &amp;old_val, int new_val, int fid)\n    {\n        if(old_val != new_val)\n        {\n            p_pkg->SetVal(new_val, fid);\n            old_val = new_val;\n        }\n    };\n\nlambda_cpy_fld(buf_x.fld_a, buf_y.fld_a, FID_A);<\/code><\/pre>\n\n\n\n<p>\u662f\u4e0d\u662f\u770b\u8d77\u6765\u5570\u55e6\u591a\u4e86\uff1f<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">7.\u53c2\u8003\u8d44\u6599<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li>C++ Primer\u4e2d\u6587\u7248 \u7b2c\u4e94\u7248 10.3.2<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>1.\u4ec0\u4e48\u662f\u5b8f\u5b9a\u4e49\u4ee3\u7801\u6bb5 C\/C++\u5b8f\u5b9a\u4e49\u5c5e\u4e8e\u9884\u5904\u7406\u9636\u6bb5\u7684\u529f\u80fd\uff0c\u64cd\u4f5c\u7684\u5bf9\u8c61\u662f\u6e90\u4ee3\u7801\u3002\u5728\u9884\u5904\u7406\u9636\u6bb5\uff0c\u7f16\u8bd1\u5668\u6839\u636e\u7528\u6237\u5b9a\u4e49\u7684\u9884\u5904\u7406\u6307\u4ee4\uff0c\u5c06\u6e90\u4ee3\u7801\u6539\u9020\u6210\u53e6\u5916\u4e00\u79cd\u5f62\u5f0f\u3002 \u9700&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"http:\/\/www.wangkaixuan.tech\/?p=925\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-925","post","type-post","status-publish","format-standard","hentry","category-03-01-"],"_links":{"self":[{"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=\/wp\/v2\/posts\/925","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=925"}],"version-history":[{"count":0,"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=\/wp\/v2\/posts\/925\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=925"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=925"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.wangkaixuan.tech\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=925"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}