{"id":68632,"date":"2025-05-11T10:34:19","date_gmt":"2025-05-11T02:34:19","guid":{"rendered":"https:\/\/fwq.ai\/blog\/?p=68632"},"modified":"2025-05-11T10:34:19","modified_gmt":"2025-05-11T02:34:19","slug":"%e6%b7%b1%e5%85%a5%e8%a7%a3%e6%9e%90%e7%8e%b0%e4%bb%a3-c-%e5%b8%b8%e9%87%8f%e6%9c%ba%e5%88%b6%ef%bc%9aconst-%e4%b8%8e-constexpr-%e7%9a%84%e6%9c%ac%e8%b4%a8%e5%8c%ba%e5%88%ab%e4%b8%8e%e5%ba%94","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/68632\/","title":{"rendered":"\u6df1\u5165\u89e3\u6790\u73b0\u4ee3 C++ \u5e38\u91cf\u673a\u5236\uff1aconst \u4e0e constexpr \u7684\u672c\u8d28\u533a\u522b\u4e0e\u5e94\u7528\u6307\u5357"},"content":{"rendered":"<h2>\u5f15\u8a00<\/h2>\n<p>\u5728\u73b0\u4ee3 C++ \u5f00\u53d1\u4e2d\uff0c\u5982\u4f55\u6b63\u786e\u5b9a\u4e49\u4e0d\u53ef\u53d8\u7684\u503c\uff0c\u662f\u63d0\u5347\u4ee3\u7801\u5065\u58ee\u6027\u4e0e\u8fd0\u884c\u6548\u7387\u7684\u5173\u952e\u6b65\u9aa4\u3002\u5c24\u5176\u662f\u5728\u8fdb\u884c\u5927\u89c4\u6a21\u7cfb\u7edf\u5f00\u53d1\u3001\u90e8\u7f72\u9ad8\u6027\u80fd\u670d\u52a1\u5e94\u7528\uff08\u4f8b\u5982\u5728<strong>\u7f8e\u56fd\u4e91\u670d\u52a1\u5668<\/strong>\u73af\u5883\u4e0b\uff09\uff0c\u7406\u89e3 <code>const<\/code> \u4e0e <code>constexpr<\/code> \u7684\u672c\u8d28\u5dee\u5f02\uff0c\u5bf9\u4e8e\u8d44\u6e90\u8c03\u5ea6\u4e0e\u6027\u80fd\u4f18\u5316\u5c24\u4e3a\u91cd\u8981\u3002\u672c\u6587\u5c06\u7cfb\u7edf\u8bb2\u89e3\u8fd9\u4e24\u4e2a\u5173\u952e\u5b57\u7684\u4e0d\u540c\u8bed\u4e49\u3001\u4f7f\u7528\u573a\u666f\uff0c\u4ee5\u53ca\u5728\u5b9e\u9645\u9879\u76ee\u4e2d\u7684\u6027\u80fd\u5f71\u54cd\u3002<\/p>\n<hr \/>\n<h2>\u5e38\u91cf\u5b9a\u4e49\u7684\u6f14\u8fdb\uff1a\u4ece const \u5230 constexpr<\/h2>\n<h3>1. <code>const<\/code>\uff1a\u4e0d\u53ef\u53d8\uff0c\u4f46\u503c\u53ef\u5728\u8fd0\u884c\u65f6\u786e\u5b9a<\/h3>\n<p>\u5728 C++ \u4e2d\uff0c<code>const<\/code> \u8868\u793a\u67d0\u4e2a\u53d8\u91cf\u5728\u521d\u59cb\u5316\u540e\u4e0d\u80fd\u88ab\u4fee\u6539\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\">const int max_connections = 100;\r\n<\/code><\/pre>\n<p>\u6b64\u5904 <code>max_connections<\/code> \u662f\u53ea\u8bfb\u7684\uff0c\u4f46\u8fd9\u4e2a\u503c\u662f\u5426\u5728\u7f16\u8bd1\u65f6\u786e\u5b9a\uff0c\u53d6\u51b3\u4e8e\u521d\u59cb\u5316\u8868\u8fbe\u5f0f\uff1a<\/p>\n<pre><code class=\"language-cpp\">const int x = 10;              \/\/ \u7f16\u8bd1\u671f\u5df2\u77e5\r\nconst int y = get_user_input(); \/\/ \u8fd0\u884c\u671f\u624d\u786e\u5b9a\r\n<\/code><\/pre>\n<p>\u5728\u670d\u52a1\u5668\u5e94\u7528\u4e2d\uff0c\u67d0\u4e9b\u914d\u7f6e\uff08\u5982\u6700\u5927\u7ebf\u7a0b\u6570\uff09\u53ef\u80fd\u6765\u81ea\u914d\u7f6e\u6587\u4ef6\u6216\u73af\u5883\u53d8\u91cf\uff0c\u8fd9\u7c7b\u5e38\u91cf\u901a\u5e38\u53ea\u80fd\u5728\u8fd0\u884c\u65f6\u7531 <code>const<\/code> \u63a7\u5236\u3002<\/p>\n<blockquote><p>\u501f\u52a9\u7f8e\u56fdVPS\u90e8\u7f72\u540e\u7aef\u670d\u52a1\u65f6\uff0c\u5c06\u914d\u7f6e\u5e38\u91cf\u901a\u8fc7 <code>const<\/code> \u5b9a\u4e49\uff0c\u53ef\u5728\u4fdd\u6301\u7075\u6d3b\u6027\u7684\u540c\u65f6\u589e\u5f3a\u4ee3\u7801\u53ef\u8bfb\u6027\u4e0e\u5b89\u5168\u6027\u3002<\/p><\/blockquote>\n<hr \/>\n<h3>2. <code>constexpr<\/code>\uff1a\u4e0d\u4ec5\u4e0d\u53d8\uff0c\u800c\u4e14\u5fc5\u987b\u7f16\u8bd1\u671f\u53ef\u77e5<\/h3>\n<p>\u81ea C++11 \u8d77\uff0c<code>constexpr<\/code> \u5f15\u5165\u4e86\u4e00\u79cd\u66f4\u5f3a\u7ea6\u675f\u2014\u2014\u8981\u6c42\u53d8\u91cf\u5728\u7f16\u8bd1\u65f6\u5373\u53ef\u786e\u5b9a\u5176\u503c\u3002\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-cpp\">constexpr int max_clients = 512;\r\nconstexpr int buffer_size = max_clients * 2;\r\n<\/code><\/pre>\n<p>\u8fd9\u79cd\u65b9\u5f0f\u9002\u7528\u4e8e\u56fa\u5b9a\u503c\u5e38\u91cf\uff08\u5982\u7f13\u5b58\u5757\u5927\u5c0f\u3001\u5904\u7406\u7ebf\u7a0b\u6570\u91cf\u7b49\uff09\uff0c\u80fd\u591f\u663e\u8457\u63d0\u9ad8\u7a0b\u5e8f\u542f\u52a8\u65f6\u7684\u8fd0\u884c\u6548\u7387\u3002\u5728\u90e8\u7f72\u4e8e\u7f8e\u56fd\u670d\u52a1\u5668\u7684\u9ad8\u5e76\u53d1\u5e94\u7528\u4e2d\uff0c\u9884\u7f16\u8bd1\u5e38\u91cf\u5c24\u5176\u80fd\u5e26\u6765\u521d\u59cb\u5316\u901f\u5ea6\u7684\u4f18\u52bf\u3002<\/p>\n<hr \/>\n<h2>\u4f7f\u7528\u573a\u666f\u5bf9\u6bd4\u4e0e\u6700\u4f73\u5b9e\u8df5<\/h2>\n<table>\n<thead>\n<tr>\n<th>\u7279\u6027\/\u5173\u952e\u5b57<\/th>\n<th>const<\/th>\n<th>constexpr<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u4e0d\u53ef\u53d8\u6027<\/td>\n<td>\u2705<\/td>\n<td>\u2705<\/td>\n<\/tr>\n<tr>\n<td>\u7f16\u8bd1\u671f\u53ef\u6c42\u503c<\/td>\n<td>\u53ef\u80fd<\/td>\n<td>\u5fc5\u987b<\/td>\n<\/tr>\n<tr>\n<td>\u4f7f\u7528\u51fd\u6570\u521d\u59cb\u5316<\/td>\n<td>\u5141\u8bb8\uff0c\u4f46\u9700\u8fd0\u884c\u65f6\u6c42\u503c<\/td>\n<td>\u4ec5\u9650\u7f16\u8bd1\u671f\u53ef\u8ba1\u7b97\u7684\u51fd\u6570<\/td>\n<\/tr>\n<tr>\n<td>\u9002\u7528\u7248\u672c<\/td>\n<td>C++98 \u53ca\u4ee5\u4e0a<\/td>\n<td>C++11 \u53ca\u4ee5\u4e0a<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u5efa\u8bae\u4f7f\u7528\u573a\u666f\uff1a<\/h3>\n<ul>\n<li><strong>\u4f7f\u7528 <code>const<\/code>\uff1a<\/strong>\n<ul>\n<li>\u7528\u6237\u8f93\u5165\u3001\u914d\u7f6e\u8bfb\u53d6\uff08\u8fd0\u884c\u65f6\u5df2\u77e5\uff09<\/li>\n<li>\u51fd\u6570\u53c2\u6570\u9632\u6b62\u4fee\u6539\uff1a<code>void process(const std::string&amp; input);<\/code><\/li>\n<li>\u6307\u9488\u4fdd\u62a4\uff1a<code>const int* ptr = &amp;val;<\/code><\/li>\n<\/ul>\n<\/li>\n<li><strong>\u4f7f\u7528 <code>constexpr<\/code>\uff1a<\/strong>\n<ul>\n<li>\u7f16\u8bd1\u65f6\u786e\u5b9a\u7684\u5e38\u91cf\u914d\u7f6e\uff08\u5982\u7f13\u51b2\u533a\u5927\u5c0f\uff09<\/li>\n<li>\u7f16\u8bd1\u65f6\u8ba1\u7b97\u8868\u8fbe\u5f0f<\/li>\n<li>\u9759\u6001\u7c7b\u6210\u5458\u5e38\u91cf\u5b9a\u4e49<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<hr \/>\n<h2>\u5b9e\u4f8b\u5206\u6790\uff1a\u6590\u6ce2\u90a3\u5951\u51fd\u6570\u7684\u6027\u80fd\u5dee\u5f02<\/h2>\n<p>\u8003\u8651\u4e0b\u9762\u4e24\u6bb5\u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"language-cpp\">\/\/ constexpr \u5b9e\u73b0\r\nconstexpr int fibonacci(int n) {\r\n    return (n &lt;= 1) ? n : fibonacci(n - 1) + fibonacci(n - 2);\r\n}\r\n\r\nconstexpr int fib10 = fibonacci(10); \/\/ \u7f16\u8bd1\u671f\u6c42\u503c\r\n<\/code><\/pre>\n<p>\u76f8\u6bd4\u4f20\u7edf\u8fd0\u884c\u65f6\u7248\u672c\uff0c<code>constexpr<\/code> \u5728\u7f16\u8bd1\u9636\u6bb5\u5c31\u5f97\u51fa\u7ed3\u679c\uff0c\u5bf9\u4e8e\u90e8\u7f72\u5728<strong>\u7f8e\u56fd\u4e91\u670d\u52a1\u5668<\/strong>\u4e0a\u7684\u5ef6\u8fdf\u654f\u611f\u5e94\u7528\u800c\u8a00\uff0c\u53ef\u4ee5\u663e\u8457\u51cf\u5c11\u521d\u59cb\u5316\u65f6\u95f4\u3002<\/p>\n<hr \/>\n<h2>C++ \u5e38\u91cf\u5b9a\u4e49\u5b9e\u8df5\u603b\u7ed3<\/h2>\n<ol>\n<li><strong>\u4f18\u5148\u8003\u8651 <code>constexpr<\/code><\/strong>\uff1a\u5982\u679c\u80fd\u5728\u7f16\u8bd1\u671f\u786e\u5b9a\uff0c\u4f18\u5148\u4f7f\u7528\u5b83\uff0c\u63d0\u5347\u6267\u884c\u6548\u7387\u3002<\/li>\n<li><strong>\u51fd\u6570\u53c2\u6570\u4e2d\u7528 <code>const<\/code><\/strong>\uff1a\u4fdd\u969c\u6570\u636e\u4e0d\u53ef\u88ab\u51fd\u6570\u4fee\u6539\uff0c\u63d0\u9ad8\u5b89\u5168\u6027\u3002<\/li>\n<li><strong>\u7c7b\u6210\u5458\u5e38\u91cf\u63a8\u8350\u4f7f\u7528 <code>static constexpr<\/code><\/strong>\uff0c\u4f8b\u5982\uff1a<\/li>\n<\/ol>\n<pre><code class=\"language-cpp\">class ServerConfig {\r\npublic:\r\n    static constexpr int kMaxThreads = 32;\r\n};\r\n<\/code><\/pre>\n<ol start=\"4\">\n<li><strong>\u5584\u7528\u7f16\u8bd1\u671f\u5e38\u91cf\u63d0\u5347\u53ef\u79fb\u690d\u6027<\/strong>\uff1a\u5c24\u5176\u5728\u8de8\u5e73\u53f0\u90e8\u7f72\uff08\u5982\u8fc1\u79fb\u81f3<strong>\u7f8e\u56fd\u670d\u52a1\u5668<\/strong>\u73af\u5883\uff09\u65f6\uff0c\u66f4\u5177\u7a33\u5b9a\u6027\u4e0e\u53ef\u63a7\u6027\u3002<\/li>\n<\/ol>\n<hr \/>\n<h2>\u7ed3\u8bed\uff1a\u638c\u63e1 const \u4e0e constexpr\uff0c\u5199\u51fa\u66f4\u9ad8\u6548\u7684\u73b0\u4ee3 C++ \u4ee3\u7801<\/h2>\n<p>\u5e38\u91cf\u5b9a\u4e49\u5e76\u975e\u7ec6\u8282\uff0c\u800c\u662f\u51b3\u5b9a\u7a0b\u5e8f\u7ed3\u6784\u4e0e\u6027\u80fd\u7684\u5173\u952e\u4e4b\u4e00\u3002\u65e0\u8bba\u662f\u8fdb\u884c\u5185\u6838\u6a21\u5757\u8bbe\u8ba1\uff0c\u8fd8\u662f\u5f00\u53d1\u4f9d\u8d56 C++ \u7684\u9ad8\u6027\u80fd\u5e94\u7528\u7cfb\u7edf\uff0c\u5408\u7406\u533a\u5206 <code>const<\/code> \u4e0e <code>constexpr<\/code> \u7684\u7528\u9014\uff0c\u90fd\u662f\u6bcf\u4e00\u4f4d\u6280\u672f\u4eba\u5458\u5fc5\u5907\u7684\u57fa\u7840\u529f\u3002<\/p>\n<p>\u90e8\u7f72\u4e8e\u9ad8\u901f\u3001\u5b89\u5168\u7684<a href=\"https:\/\/fwq.ai\/\"><strong>\u7f8e\u56fd\u670d\u52a1\u5668<\/strong><\/a>\u73af\u5883\u65f6\uff0c\u66f4\u9700\u8981\u7ec6\u81f4\u6253\u78e8\u6bcf\u4e00\u884c C++ \u4ee3\u7801\uff0c\u8ba9\u7cfb\u7edf\u5728\u9ad8\u8d1f\u8f7d\u4e0b\u4f9d\u65e7\u7a33\u5b9a\u8fd0\u884c\u3002\u5982\u9700\u4e86\u89e3\u66f4\u591a\u5173\u4e8e C++ \u9ad8\u6027\u80fd\u90e8\u7f72\u4e0e\u670d\u52a1\u5668\u914d\u7f6e\u4f18\u5316\uff0c\u6b22\u8fce\u8bbf\u95ee\u6211\u4eec\u63d0\u4f9b\u7684\u9ad8\u6027\u80fd\u4e91\u670d\u52a1\u5e73\u53f0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5f15\u8a00 \u5728\u73b0\u4ee3 C++ \u5f00\u53d1\u4e2d\uff0c\u5982\u4f55\u6b63\u786e\u5b9a\u4e49\u4e0d\u53ef\u53d8\u7684\u503c\uff0c\u662f\u63d0\u5347\u4ee3\u7801\u5065\u58ee\u6027\u4e0e\u8fd0\u884c\u6548\u7387\u7684\u5173\u952e\u6b65\u9aa4\u3002\u5c24\u5176\u662f\u5728\u8fdb\u884c\u5927\u89c4\u6a21\u7cfb\u7edf\u5f00\u53d1\u3001\u90e8\u7f72\u9ad8\u6027\u80fd\u670d\u52a1\u5e94\u7528\uff08\u4f8b\u5982\u5728\u7f8e\u56fd\u4e91\u670d\u52a1\u5668\u73af\u5883\u4e0b\uff09\uff0c\u7406\u89e3 const \u4e0e constexpr \u7684\u672c\u8d28\u5dee\u5f02\uff0c\u5bf9\u4e8e\u8d44\u6e90\u8c03\u5ea6\u4e0e\u6027\u80fd\u4f18\u5316\u5c24\u4e3a\u91cd\u8981\u3002\u672c\u6587\u5c06\u7cfb\u7edf\u8bb2\u89e3\u8fd9\u4e24\u4e2a\u5173\u952e\u5b57\u7684\u4e0d\u540c\u8bed\u4e49\u3001\u4f7f\u7528\u573a\u666f\uff0c\u4ee5\u53ca\u5728\u5b9e\u9645\u9879\u76ee\u4e2d\u7684\u6027\u80fd\u5f71\u54cd\u3002 \u5e38\u91cf\u5b9a\u4e49\u7684\u6f14\u8fdb\uff1a\u4ece const \u5230 constexpr 1. const\uff1a\u4e0d\u53ef\u53d8\uff0c\u4f46\u503c\u53ef\u5728\u8fd0\u884c\u65f6\u786e\u5b9a \u5728 C++ \u4e2d\uff0cconst \u8868\u793a\u67d0\u4e2a\u53d8\u91cf\u5728\u521d\u59cb\u5316\u540e\u4e0d\u80fd\u88ab\u4fee\u6539\u3002\u4f8b\u5982\uff1a const int max_connections = 100; \u6b64\u5904 max_connections \u662f\u53ea\u8bfb\u7684\uff0c\u4f46\u8fd9\u4e2a\u503c\u662f\u5426\u5728\u7f16\u8bd1\u65f6\u786e\u5b9a\uff0c\u53d6\u51b3\u4e8e\u521d\u59cb\u5316\u8868\u8fbe\u5f0f\uff1a const int x = 10; \/\/ \u7f16\u8bd1\u671f\u5df2\u77e5 const int y = get_user_input(); \/\/ \u8fd0\u884c\u671f\u624d\u786e\u5b9a \u5728\u670d\u52a1\u5668\u5e94\u7528\u4e2d\uff0c\u67d0\u4e9b\u914d\u7f6e\uff08\u5982\u6700\u5927\u7ebf\u7a0b\u6570\uff09\u53ef\u80fd\u6765\u81ea\u914d\u7f6e\u6587\u4ef6\u6216\u73af\u5883\u53d8\u91cf\uff0c\u8fd9\u7c7b\u5e38\u91cf\u901a\u5e38\u53ea\u80fd\u5728\u8fd0\u884c\u65f6\u7531 const \u63a7\u5236\u3002 \u501f\u52a9\u7f8e\u56fdVPS\u90e8\u7f72\u540e\u7aef\u670d\u52a1\u65f6\uff0c\u5c06\u914d\u7f6e\u5e38\u91cf\u901a\u8fc7 const \u5b9a\u4e49\uff0c\u53ef\u5728\u4fdd\u6301\u7075\u6d3b\u6027\u7684\u540c\u65f6\u589e\u5f3a\u4ee3\u7801\u53ef\u8bfb\u6027\u4e0e\u5b89\u5168\u6027\u3002 2. constexpr\uff1a\u4e0d\u4ec5\u4e0d\u53d8\uff0c\u800c\u4e14\u5fc5\u987b\u7f16\u8bd1\u671f\u53ef\u77e5 \u81ea C++11 \u8d77\uff0cconstexpr \u5f15\u5165\u4e86\u4e00\u79cd\u66f4\u5f3a\u7ea6\u675f\u2014\u2014\u8981\u6c42\u53d8\u91cf\u5728\u7f16\u8bd1\u65f6\u5373\u53ef\u786e\u5b9a\u5176\u503c\u3002\u793a\u4f8b\u5982\u4e0b\uff1a constexpr int max_clients [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-68632","post","type-post","status-publish","format-standard","hentry","category-coding"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/68632","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=68632"}],"version-history":[{"count":1,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/68632\/revisions"}],"predecessor-version":[{"id":68634,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/68632\/revisions\/68634"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=68632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=68632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=68632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}