{"id":165047,"date":"2020-10-03T11:03:02","date_gmt":"2020-10-03T03:03:02","guid":{"rendered":"http:\/\/4563.org\/?p=165047"},"modified":"2020-10-10T06:38:11","modified_gmt":"2020-10-09T22:38:11","slug":"%e7%bf%bb%e8%af%91-const-%e6%98%af%e5%90%a6%e4%bc%9a%e5%af%b9%e7%a8%8b%e5%ba%8f%e7%9a%84%e4%bc%98%e5%8c%96%e4%ba%a7%e7%94%9f%e5%bd%b1%e5%93%8d","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=165047","title":{"rendered":"[\u7ffb\u8bd1] const \u662f\u5426\u4f1a\u5bf9\u7a0b\u5e8f\u7684\u4f18\u5316\u4ea7\u751f\u5f71\u54cd"},"content":{"rendered":"
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[\u7ffb\u8bd1] const \u662f\u5426\u4f1a\u5bf9\u7a0b\u5e8f\u7684\u4f18\u5316\u4ea7\u751f\u5f71\u54cd <\/h1>\n

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\u8cc7\u6df1\u5927\u4f6c : wzzzx <\/span> <\/i> 3<\/span> <\/div>\n
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\u6765\u6e90\uff1ahttp:\/\/www.gotw.ca\/gotw\/081.htm<\/code><\/p>\n

1. \u51fd\u6570\u53c2\u6570\u58f0\u660e\u4e3aconst<\/code>\u548c\u8fd4\u56de\u503c\u58f0\u660e\u4e3aconst<\/code>\uff0c\u662f\u5426\u4f1a\u5bf9\u7f16\u8bd1\u5668\u4f18\u5316\u4ee3\u7801\u4ea7\u751f\u5f71\u54cd\uff1f<\/h3>\n
  \/\/ Example 1   \/\/   const Y& f( const X& x )   {     \/\/ ... do something with x and find a Y object ...     return someY;   } <\/code><\/pre>\n
\u7b80\u8981\u5730\u8bf4\uff0c\u4e5f\u8bb8\u5e76\u4e0d\u4f1a\u3002 \u7f16\u8bd1\u5668\u80fd\u505a\u7684\u66f4\u597d\u7684\u662f\u4ec0\u4e48\uff1f\u5b83\u80fd\u591f\u907f\u514d\u4f20\u53c2\u548c\u8fd4\u56de\u503c\u7684\u62f7\u8d1d\u5f00\u9500\u5417\uff1f\u5e76\u4e0d\uff0c\u56e0\u4e3a\u53c2\u6570\u548c\u8fd4\u56de\u503c\u662f\u901a\u8fc7\u5f15\u7528\u6765\u8fdb\u884c\u4f20\u9012\u7684\u3002\u5b83\u80fd\u591f\u5c06x<\/code>\u548csomeY<\/code>\u62f7\u8d1d\u5230\u53ea\u8bfb\u5185\u5b58\u533a\u57df\u5417\uff1f\u4e5f\u4e0d\u4f1a\u3002\u5bf9\u4e8ex<\/code>\u548csomeY<\/code>\u800c\u8a00\uff0c\u5b83\u4eec\u7684\u751f\u547d\u5468\u671f\u5747\u5728\u8be5\u51fd\u6570\u7684\u4f5c\u7528\u57df\u4e4b\u5916\u3002\u5373\u4fbfsomeY<\/code>\u662f\u5728\u51fd\u6570\u5185\u90e8\u52a8\u6001\u521b\u5efa\u7684\uff0c\u5b83\u7684\u6240\u6709\u6743\u4e5f\u4f1a\u88ab\u4f20\u9012\u7ed9\u8c03\u7528\u8005\u3002 \u4f46\u5728f()<\/code>\u7684\u5185\u90e8\uff0c\u6709\u6ca1\u6709\u53ef\u80fd\u4f1a\u5bf9\u4ee3\u7801\u8fdb\u884c\u4e00\u5b9a\u7684\u4f18\u5316\u5462\uff1f\u56e0\u4e3aconst<\/code>\u7684\u5b58\u5728\uff0c\u4f1a\u4e0d\u4f1a\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u5bfc\u81f4\u7f16\u8bd1\u5668\u751f\u6210\u66f4\u52a0\u4f18\u5316\u7684\u4ee3\u7801\u5462\uff1f<\/p>\n
2. \u4ece\u4e00\u822c\u5316\u7684\u60c5\u51b5\u6765\u770b\uff0c\u4f7f\u7528\u4e0e\u5426const<\/code>\u4e3a\u4ec0\u4e48\u4f1a\u5bf9\u7f16\u8bd1\u5668\u7684\u4ee3\u7801\u4f18\u5316\u4ea7\u751f\u5f71\u54cd<\/h3>\n
\u56de\u5230Example 1<\/code>\uff0c\u4f7f\u7528const<\/code>\u4fee\u9970\u53c2\u6570\u4e0d\u4f1a\u5bfc\u81f4\u7f16\u8bd1\u5668\u5bf9\u4ee3\u7801\u4ea7\u751f\u989d\u5916\u4f18\u5316\u7684\u539f\u56e0\u662f\uff0c\u5373\u4fbf\u8c03\u7528\u4e00\u4e2aconst<\/code>\u7c7b\u6210\u5458\u51fd\u6570\uff0c\u7f16\u8bd1\u5668\u4e5f\u6ca1\u6cd5\u8ba4\u5b9ax<\/code>\u548csomeY<\/code>\u7684\u503c\u4e0d\u4f1a\u53d1\u751f\u6539\u53d8\u3002\u518d\u8005\uff0c\u9664\u975e\u7f16\u8bd1\u5668\u8fdb\u884c\u5168\u5c40\u4f18\u5316\uff0c\u4e0d\u7136\u4f1a\u6709\u5176\u4ed6\u7684\u4e00\u4e9b\u95ee\u9898\u5b58\u5728\uff1a\u9996\u5148\uff0c\u7f16\u8bd1\u5668\u5e76\u4e0d\u77e5\u9053\u5176\u4ed6\u7684\u4ee3\u7801\u4f1a\u4e0d\u4f1a\u6301\u6709\u5bf9\u8c61x<\/code>\u548csomeY<\/code>\u7684\u975econst<\/code>\u5f15\u7528\uff0c\u8fd9\u4e9b\u53d8\u91cf\u53ef\u80fd\u4f1a\u5728f()<\/code>\u6267\u884c\u671f\u95f4\u88ab\u610f\u5916\u5730\u4f7f\u7528\u3002\u5176\u6b21\uff0c\u7f16\u8bd1\u5668\u4e5f\u4e0d\u4e00\u5b9a\u4f1a\u77e5\u9053\uff0cx<\/code>\u548cxomeY<\/code>\u6240\u5f15\u7528\u7684\u5bf9\u8c61\uff0c\u662f\u5426\u662f\u88ab\u4e3b\u52a8\u58f0\u660e\u4e3a\u4e00\u4e2aconst<\/code>\u53d8\u91cf\u3002 \u4ec5\u4ec5\u56e0\u4e3ax<\/code>\u548cy<\/code>\u88ab\u58f0\u660e\u4e3aconst<\/code>\u5e38\u91cf\uff0c\u4e5f\u4e0d\u4e00\u5b9a\u610f\u5473\u5b83\u4eec\u7269\u7406\u4e0a\u7684\u4f4d\u662f\u5e38\u91cf\u3002\u56e0\u4e3a\u8fd9\u4e9b\u7c7b\u53ef\u80fd\u4f1a\u5b58\u5728\u53ef\u53d8\u6210\u5458\uff0c\u6216\u8005\u5176\u4ed6\u7b49\u4ef7\u7684\u4e1c\u897f\uff0c\u5373\u5728\u6210\u5458\u51fd\u6570\u5185\u90e8\u8fdb\u884cconst_cast<\/code>\u5f3a\u5236\u8f6c\u6362\u6216\u8005C<\/code>\u8bed\u8a00\u6837\u5f0f\u7684\u5f3a\u5236\u8f6c\u6362\uff0c\u5bfc\u81f4\u88ab\u58f0\u660e\u4e3aconst<\/code>\u5e38\u91cf\u5e76\u4e0d\u662f\u4e00\u4e2a\u771f\u6b63\u7684\u5e38\u91cf\u3002 \u53ea\u6709\u5728\u53d8\u91cf\u5b9a\u4e49\u7684\u65f6\u5019\uff0c\u58f0\u660e\u4e3aconst<\/code>\u5e38\u91cf\uff0c\u6b64\u65f6\u8bf4const<\/code>\u5e38\u91cf\u624d\u5177\u6709\u610f\u4e49\u3002\u7279\u522b\u662f\u8fd9\u4e9b\u53d8\u91cf\u662f\u80fd\u591f\u5728\u7f16\u8bd1\u671f\u95f4\u5c31\u751f\u6210\u7684POD<\/code>\u7c7b\u578b\u65f6\uff0c\u7f16\u8bd1\u5668\u53ef\u4ee5\u5c06\u8fd9\u4e9b\u771f\u6b63\u7684const<\/code>\u5e38\u91cf\u5bf9\u8c61\u653e\u7f6e\u5230\u53ea\u8bfb\u5185\u5b58\u4e2d\uff0c\u540c\u65f6\u4f1a\u88ab\u5b58\u50a8\u5230\u53ef\u6267\u884c\u6587\u4ef6\u672c\u8eab\u3002\u8fd9\u6837\u7684\u5bf9\u8c61\u4f1a\u88ab\u79f0\u4e3aROM-able<\/code><\/p>\n
3. \u4f9d\u4e0b\u5217\u4ee3\u7801\u8003\u8651\u4e09\u4e2a\u5c0f\u95ee\u9898\uff1a<\/h3>\n
  \/\/ Example 3   \/\/   void f( const Z z )   {     \/\/ ...   } <\/code><\/pre>\n
\u6709\u4e09\u4e2a\u5c0f\u95ee\u9898\u9700\u8981\u601d\u8003\uff1a<\/p>\n
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  1. \u4ec0\u4e48\u73af\u5883\u4e0b\uff0c\u67d0\u4e9b\u7279\u5b9a\u7c7b\u578b\u7684Z<\/code>\u662f\u5426\u53ef\u4ee5\u4f7f\u7f16\u8bd1\u5668\u751f\u6210\u4e0d\u4e00\u6837\u4e14\u66f4\u597d\u7684\u4ee3\u7801\uff1f<\/strong><\/li>\n
  2. \u5728\u95ee\u9898 a \u6240\u63d0\u53ca\u7684\u60c5\u51b5\u4e0b\uff0c \u6211\u4eec\u662f\u5728\u8ba8\u8bba\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u8fd8\u662f\u5176\u4ed6\u65b9\u9762\u7684\u4f18\u5316\u3002<\/strong><\/li>\n
  3. \u6709\u66f4\u597d\u7684\u53d6\u5f97\u76f8\u540c\u7684\u6548\u679c\u5417\uff1f<\/strong><\/li>\n<\/ol>\n
    3.1 \u4ec0\u4e48\u73af\u5883\u4e0b\uff0c\u67d0\u4e9b\u7279\u5b9a\u7c7b\u578b\u7684Z<\/code>\u662f\u5426\u53ef\u4ee5\u4f7f\u7f16\u8bd1\u5668\u751f\u6210\u4e0d\u4e00\u6837\u4e14\u66f4\u597d\u7684\u4ee3\u7801\uff1f<\/strong><\/h4>\n
    \u7b80\u8981\u56de\u7b54\u5c31\u662f\uff1a\u80fd\uff0c\u4e5f\u4e0d\u80fd\u3002 \u5148\u8bf4\u4e00\u4e0b\u80fd\u7684\u90e8\u5206\u3002\u56e0\u4e3a\u7f16\u8bd1\u5668\u77e5\u9053z<\/code>\u662f\u4e00\u4e2a\u771f\u6b63\u7684\u5e38\u91cf\u5bf9\u8c61\uff0c\u6240\u4ee5\u53ef\u4ee5\u5728\u6ca1\u6709\u8fdb\u884c\u5168\u5c40\u4f18\u5316\u7684\u60c5\u51b5\u4e0b\uff0c\u8fdb\u884c\u4e00\u4e9b\u6709\u7528\u7684\u4f18\u5316\u3002\u4f8b\u5982\uff0c\u5982\u679c\u5728f()<\/code>\u5185\u6709\u4e00\u4e2a\u8fd9\u6837\u7684\u8c03\u7528\uff1ag(&z)<\/code>\u3002\u7f16\u8bd1\u5668\u53ef\u4ee5\u660e\u786e\u5730\u77e5\u9053\u5728\u8c03\u7528g()<\/code>\u7684\u65f6\u5019\uff0cz<\/code>\u4e0d\u4f1a\u53d1\u751f\u53d8\u5316\u3002 \u9664\u6b64\u4e4b\u5916\uff0c\u5728\u53c2\u6570\u503c\u58f0\u660e\u4e3aconst<\/code>\u5e38\u91cf\uff0c\u5bf9\u4e8e\u5927\u591a\u6570\u7684z<\/code>\u800c\u8a00\uff0c\u5e76\u4e0d\u4f1a\u4ea7\u751f\u4efb\u4f55\u5f62\u5f0f\u7684\u4f18\u5316\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u7684\u4f18\u5316\uff0c\u5e76\u4e0d\u662f\u7f16\u8bd1\u5668\u4ee3\u7801\u751f\u6210\u4f18\u5316\u3002 \u5bf9\u4e8e\u7f16\u8bd1\u5668\u4ee3\u7801\u751f\u6210\u4f18\u5316\uff0c\u95ee\u9898\u4e3b\u8981\u5f52\u7ed3\u4e3a\u7f16\u8bd1\u5668\u662f\u5426\u53ef\u4ee5\u7701\u7565\u62f7\u8d1d\u6784\u9020\uff0c\u6216\u8005\u662f\u5426\u53ef\u4ee5\u5c06z<\/code>\u653e\u5165\u53ea\u8bfb\u5185\u5b58\u4e2d\u3002\u8fd9\u610f\u5473\u7740\uff0c\u5bf9\u8c61z<\/code>\u5728f()<\/code>\u51fd\u6570\u5185\u90e8\u4e0d\u4f1a\u53d7\u5230\u4efb\u4f55\u7684\u5f71\u54cd\uff0c\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528\u51fd\u6570\u5916\u90e8\u7684\u5bf9\u8c61\u800c\u4e0d\u9700\u8981\u591a\u4e00\u6b21\u7684\u62f7\u8d1d\u8d4b\u503c\u64cd\u4f5c\u3002\u6216\u8005\u5373\u4fbf\u9700\u8981\u62f7\u8d1d\uff0c\u4e5f\u53ef\u4ee5\u76f4\u63a5\u5c06\u62f7\u8d1d\u540e\u7684\u5bf9\u8c61\u76f4\u63a5\u653e\u7f6e\u5728\u53ea\u8bfb\u5185\u5b58\u4e2d\uff0c\u7528\u5230\u7684\u65f6\u5019\u76f4\u63a5\u8bfb\u53d6\u3002 \u4e00\u822c\u60c5\u51b5\u4e0b\uff0c\u7f16\u8bd1\u5668\u4e0d\u4f1a\u56e0\u4e3a\u53c2\u6570\u662fconst<\/code>\u7684\u5c31\u4e3b\u52a8\u6d88\u9664\u62f7\u8d1d\u6784\u9020\u51fd\u6570\u3002\u5982\u540c\u4e0a\u6587\u6240\u63d0\u5230\u7684\u4e00\u6837\uff0c\u8fd9\u53ef\u80fd\u4f1a\u5bfc\u81f4\u592a\u591a\u7684\u95ee\u9898\u3002\u5c24\u5176\u662fZ<\/code>\u62e5\u6709\u53ef\u53d8\u6210\u5458\u7684\u65f6\u5019\uff0c\u6216\u8005\u5728\u5176\u4ed6\u5730\u65b9\u76f4\u63a5\u6216\u95f4\u63a5\u4f7f\u7528\u5230Z<\/code>\u7684\u6210\u5458\u51fd\u6570\u65f6\uff0c\u53ef\u80fd\u4f1a\u4f7f\u7528const_casts<\/code>\u6765\u6539\u53d8\u5e38\u91cf\u3002 \u4f46\u6709\u4e00\u4e9b\u529e\u6cd5\u6765\u5e2e\u52a9\u7f16\u8bd1\u5668\u751f\u6210\u66f4\u597d\u7684\u4ee3\u7801\uff0c\u5982\u4e0b\u51e0\u70b9\uff1a<\/p>\n
      \n
    • \u5bf9\u4e8eZ<\/code>\u7684\u62f7\u8d1d\u6784\u9020\u51fd\u6570\u548c\u6240\u6709\u5728f()<\/code>\u4e2d\u76f4\u63a5\u6216\u95f4\u63a5\u7528\u5230\u7684\u6210\u5458\u51fd\u6570\u90fd\u662f\u53ef\u89c1\u7684\u3002<\/li>\n
    • \u8fd9\u4e9b\u51fd\u6570\u90fd\u975e\u5e38\u7b80\u5355\u4e14\u6ca1\u6709\u4efb\u4f55\u526f\u4f5c\u7528<\/li>\n
    • \u7f16\u8bd1\u5668\u6709\u8f83\u4e3a\u6fc0\u8fdb\u7684\u4f18\u5316\u7b56\u7565<\/li>\n<\/ul>\n
      \u6ee1\u8db3\u4e0a\u8ff0\u4e09\u70b9\u4f1a\u8ba9\u7f16\u8bd1\u5668\u660e\u786e\u6bcf\u4e00\u6b65\u5177\u4f53\u53d1\u751f\u4e86\u4ec0\u4e48\uff0c\u6240\u4ee5\u7f16\u8bd1\u5668\u80fd\u591f\u5728as-if<\/code>\u89c4\u5219\u7684\u9650\u5236\u4e0b\uff0c\u81ea\u4e3b\u9009\u62e9\u6d88\u9664\u4e00\u4e9b\u4e0d\u5fc5\u8981\u7684\u4ee3\u7801\u3002 \u53e6\u5916\uff0c\u8fd8\u6709\u4e00\u70b9\u503c\u5f97\u4e00\u63d0\u3002\u6709\u4e9b\u4eba\u4f1a\u8bf4\u7f16\u8bd1\u5668\u6267\u884c\u5168\u5c40\u4f18\u5316\u7684\u65f6\u5019\uff0c\u53ef\u4ee5\u5bf9const<\/code>\u5e38\u91cf\u63d0\u4f9b\u4f18\u5316\u4ee5\u751f\u6210\u66f4\u597d\u7684\u4ee3\u7801\u3002\u4e8b\u5b9e\u4e0a\uff0c\u5373\u4fbf\u53bb\u6389const<\/code>\u4fee\u9970\uff0c\u4e5f\u53ef\u4ee5\u5bf9\u751f\u6210\u4ee3\u7801\u8fdb\u884c\u4f18\u5316\u3002\u4e0d\u8981\u4ecb\u610f\u5168\u5c40\u4f18\u5316\u7684\u9891\u6b21\u4f4e\u4e14\u4ee3\u4ef7\u9ad8\u3002\u8fd9\u91cc\u771f\u6b63\u7684\u95ee\u9898\u662f\u5168\u5c40\u4f18\u5316\u6e05\u695a\u6240\u6709\u5bf9\u8c61\u7684\u771f\u6b63\u4f7f\u7528\u60c5\u51b5\uff0c\u6240\u4ee5\u4e0d\u7ba1\u6709\u65e0\u58f0\u660e\u4e3aconst<\/code>\uff0c\u90fd\u4f1a\u6267\u884c\u76f8\u540c\u7684\u4f18\u5316\u64cd\u4f5c\u3002\u5168\u5c40\u4f18\u5316\u9488\u5bf9\u7684\u662f\u4f60\u771f\u6b63\u7684\u64cd\u4f5c\uff0c\u800c\u4e0d\u662f\u4f60\u627f\u8bfa\u4f1a\u505a\u7684\u64cd\u4f5c\u3002\u56e0\u6b64\u5982\u679c\u4f60\u6267\u884c\u4e86\u771f\u6b63\u7684\u5168\u5c40\u4f18\u5316\uff0cconst<\/code>\u7684\u58f0\u660e\u5e76\u4e0d\u4f1a\u5bf9\u4f18\u5316\u5668\u4ea7\u751f\u4efb\u4f55\u7684\u5f71\u54cd\u3002 \u6ce8\u610f\u4e0a\u6587\u6240\u8bf4\u7684\uff0cExample 3<\/code>\u4e2d\u7684\u5927\u591a\u6570Z<\/code>\u58f0\u660e\u4e3aconst<\/code>\u5bf9\u7f16\u8bd1\u5668\u751f\u6210\u4ee3\u7801\u5e76\u4e0d\u4f1a\u6709\u4efb\u4f55\u7684\u4f18\u5316\u3002\u7136\u800c\uff0c\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u5668\u8fd8\u662f\u53ef\u80fd\u5b58\u5728\u4e00\u4e9b\u4f18\u5316\u7684\u3002\u5b9e\u9645\u4e0a\uff0cconst<\/code>\u4e5f\u53ef\u4ee5\u6709\u4e00\u4e9b\u771f\u6b63\u7684\u4f18\u5316\u7684\u3002<\/p>\n
      \u5728\u95ee\u9898 3.1 \u6240\u63d0\u53ca\u7684\u60c5\u51b5\u4e0b\uff0c \u6211\u4eec\u662f\u5728\u8ba8\u8bba\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u8fd8\u662f\u5176\u4ed6\u65b9\u9762\u7684\u4f18\u5316\u3002<\/strong><\/h4>\n
      \u5b9e\u9645\u4e0a\u5b58\u5728\u7a0b\u5e8f\u6027\u7684\u4f18\u5316\uff0cZ<\/code>\u53ef\u4ee5\u667a\u80fd\u7684\u9009\u62e9\u4e0d\u540c\u7684\u65b9\u5f0f\u6765\u9488\u5bf9const<\/code>\u5bf9\u8c61\u3002\u4f5c\u4e3a\u4f8b\u5b50\uff0c\u6211\u4eec\u53ef\u4ee5\u8ba4\u4e3aZ<\/code>\u662f\u4e00\u4e2ahandle<\/code>\u7c7b\uff0c\u4f8b\u5982String<\/code>\u4f1a\u4f7f\u7528\u5f15\u7528\u8ba1\u6570\u6765\u5b8c\u6210\u61d2\u590d\u5236\u3002<\/p>\n
        \/\/ Example 4   \/\/   void f( const String s )   {     \/\/ ...     s[4]; \/\/ or use iterators     \/\/ ...   } <\/code><\/pre>\n
      \u7c7b\u4f3c\u4e8eString<\/code>\uff0c\u5bf9\u6709const<\/code>\u4fee\u9970\u7684String<\/code>\u6267\u884coperator[]()<\/code>\u65f6\uff0c\u4e0d\u53ef\u4ee5\u4fee\u6539\u5b57\u7b26\u4e32\u7684\u5185\u5bb9\uff0c\u8fd9\u4e5f\u8bb8\u53ef\u4ee5\u63d0\u4f9b\u4e00\u4e2a\u91cd\u8f7d\u51fd\u6570\uff0c\u8be5\u51fd\u6570\u8fd4\u56de\u503c\u800c\u975e\u5f15\u7528\u3002<\/p>\n
        class String   {     \/\/ ...   public:     char  operator[]( size_t ) const;     char& operator[]( size_t );     \/\/ ...   } <\/code><\/pre>\n
      \u7c7b\u4f3c\u4e8e\uff0cString<\/code>\u4e5f\u53ef\u4ee5\u63d0\u4f9bconst_iterators<\/code>\uff0c\u8c03\u7528operator*()<\/code>\u4f1a\u8fd4\u56de\u503c\u800c\u975e\u5f15\u7528\u3002 \u5982\u679c\u4f60\u4f7f\u7528operator[]()<\/code>\u6216iterators<\/code>\uff0c\u5e76\u4e14\u4f20\u53c2\u65f6\u4f7f\u7528const<\/code>\u4fee\u9970\uff0c\u4f60\u4f1a\u53d1\u73b0\uff0cString<\/code>\u4f1a\u81ea\u52a8\u5730\u5e2e\u52a9\u4f60\u907f\u514d\u6df1\u62f7\u8d1d\u3002<\/p>\n
      3.3 \u6709\u66f4\u597d\u7684\u53d6\u5f97\u76f8\u540c\u7684\u6548\u679c\u5417\uff1f<\/strong><\/h4>\n
      \u4f60\u53ef\u4ee5\u901a\u8fc7\u7b80\u5355\u7684\u65b9\u6cd5\u6765\u83b7\u5f97\u4e0a\u8ff0\u6548\u679c\u3002<\/p>\n
        \/\/ Example 5: Just do it -- better than Example 3   \/\/   void f( const Z& z )   {     \/\/ ...   } <\/code><\/pre>\n
      \u73b0\u5728\u4e0d\u7ba1\u5bf9\u8c61\u662f\u4e0d\u662f\u4e00\u4e2ahandle<\/code>\u7c7b\u6216\u5f15\u7528\u8ba1\u6570\u7684\u4e1c\u897f\uff0c\u90fd\u53ef\u4ee5\u5b9e\u73b0\u907f\u514d\u6df1\u5ea6\u62f7\u8d1d\u7684\u4f18\u5316\u3002\u8fd9\u4e5f\u662f\u4e00\u4e2a\u51c6\u5219\uff0c\u4f7f\u7528const<\/code>\u5f15\u7528\u7684\u65b9\u5f0f\u6765\u4f20\u9012\u53c2\u6570\uff0c\u800c\u4e0d\u662f\u7b80\u5355\u7684const<\/code>\u503c\u4f20\u9012\u3002 \u8fd9\u6837\u53ef\u4ee5\u5e2e\u52a9\u7f16\u8bd1\u5668\u751f\u6210\u66f4\u7d27\u51d1\u7684\u4ee3\u7801\u3002const<\/code>\u662f\u4e00\u4e2a\u597d\u4e1c\u897f\uff0c\u4f46\u662f\u66f4\u591a\u7684\u662f\u5bf9\u4eba\u7c7b\u800c\u8a00\u3002\u5f53\u5e0c\u671b\u5199\u51fa\u5b89\u5168\u7684\u4ee3\u7801\u7684\u65f6\u5019\uff0cconst<\/code>\u53ef\u4ee5\u5f3a\u5236\u7f16\u8bd1\u5668\u8fdb\u884c\u68c0\u6d4b\u3002\u5728\u4f18\u5316\u9636\u6bb5\uff0cconst<\/code>\u4e5f\u662f\u4e00\u4e2a\u6709\u7528\u7684\u5de5\u5177\uff0c\u7528\u4e8e\u5e2e\u52a9\u7c7b\u8bbe\u8ba1\u8005\u5b9e\u73b0\u624b\u52a8\u4f18\u5316\uff0c\u4f46\u662f\u5bf9\u7f16\u8bd1\u5668\u4f18\u5316\u751f\u6210\u4ee3\u7801\u8fd9\u65b9\u9762\u5374\u6ca1\u6709\u90a3\u4e48\u5927\u7684\u5e2e\u52a9\u3002<\/p>\n<\/p><\/div>\n
       \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (5<\/span>)        <\/div>\n
       <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
        \n
      • \n
        \n
        \n
         \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : wzzzx <\/span>  <\/div>\n
         <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                     \u4e4b\u6240\u4ee5\u7ffb\u8bd1\u8fd9\u4e2a\u662f\u56e0\u4e3a\u524d\u9635\u5b50\u8ddf\u670b\u53cb\u8ba8\u8bba\u5230 const \u5bf9\u4e8e\u4ee3\u7801\u4f18\u5316\u7684\u5f71\u54cd\uff0c\u7136\u540e\u67e5\u770b\u5230\u4e86\u8fd9\u4e2a\u535a\u5ba2\u3002\u6240\u4ee5\u4eca\u513f\u62bd\u7a7a\u505a\u4e86\u4e00\u4e2a\u7ffb\u8bd1\uff0c\u6709\u4e0d\u597d\u7406\u89e3\u7684\u5730\u65b9\u6b22\u8fce\u6307\u51fa~                                                            <\/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
                                                                     \u539f\u4f5c\u8005\u6ca1\u6709\u8003\u8651 alias \u5206\u6790\u7684\u95ee\u9898\uff0c\u867d\u7136\u4e3a\u4e86\u7167\u987e\u7a0b\u5e8f\u5458\u5f88\u591a\u7f16\u8bd1\u5668\u662f\u5f88\u4fdd\u5b88\u7684\uff0c\u4f46\u662f\u6709\u4e9b\u7f16\u8bd1\u5668\u53ef\u4ee5\u5bf9 const \u5f15\u7528\u505a\u66f4\u4e3a\u6fc0\u8fdb\u7684\u4f18\u5316<\/p>\n
        https:\/\/software.intel.com\/content\/www\/us\/en\/develop\/documentation\/cpp-compiler-developer-guide-and-reference\/top\/compiler-reference\/compiler-options\/compiler-option-details\/advanced-optimization-options\/alias-const-qalias-const.html?language=en                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
      • \n
        \n
        \n
         \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : wzzzx <\/span>  <\/div>\n
         <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                     @codehz #2 alias \u5206\u6790\u8fd8\u662f\u7b2c\u4e00\u6b21\u542c\u8bf4\uff0c\u521a\u521a\u770b\u4e86\u4e0b\u76f8\u5173\u7684\u4e1c\u897f\uff0c\u53d1\u73b0\u8fd9\u53c8\u662f\u4e00\u4e2a\u5927\u95ee\u9898\u4e86\u3002\"[\u7ffb\u8bd1] \"[\u7ffb\u8bd1] \"[\u7ffb\u8bd1] <\/div>\n<\/p><\/div>\n<\/li>\n
      • \n
        \n
        \n
         \u8cc7\u6df1\u5927\u4f6c : 12101111 <\/span>  <\/div>\n
         <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                     \u5efa\u8bae\u6807\u9898\u4e0a\u6807\u4e0a C++, const \u7684\u8bed\u4e49\u5728\u4e0d\u540c\u8bed\u8a00\u4e2d\u662f\u4e0d\u4e00\u6837\u7684,\u540c\u65f6\u5177\u6709 immutable \u548c compile time constant \u4e24\u79cd\u8bed\u4e49,\u7f16\u8bd1\u5668\u80fd\u505a\u51fa\u7684\u4f18\u5316\u4e5f\u662f\u4e0d\u4e00\u6837\u7684.immutable \u76f8\u5bf9\u800c\u8a00\u80fd\u505a\u7684\u4f18\u5316\u66f4\u5c11,\u4f46\u662f\u53ef\u4ee5\u6709\u6548\u7684\u907f\u514d\u4e00\u4e9b bug.
        alias \u5206\u6790\u7406\u8bba\u4e0a\u53ef\u884c\u4f46\u662f\u5de5\u7a0b\u4e0a\u5f88\u96be\u505a\u5230,rustc \u5728\u542f\u7528 no alias \u65f6 LLVM \u4f1a\u7f16\u8bd1\u51fa\u9519\u8bef\u7684\u7ed3\u679c,\u800c C\/C++\u4e0d\u9760\u7a0b\u5e8f\u5458\u4e3b\u52a8\u6807\u8bb0\u5f88\u96be\u5f97\u5230\u79ef\u6781\u7684\u7ed3\u679c.                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
      • \n
        \n
        \n
         \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : wzzzx <\/span>  <\/div>\n
         <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                     @12101111 #4 \u5b66\u4e60\u4e86\u3002\u6211\u73b0\u5728\u53bb\u4e86\u89e3\u4e00\u4e0b\u5173\u4e8e immutable \u548c compile time constant \u7684\u77e5\u8bc6\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
      • \n","protected":false},"excerpt":{"rendered":"
        [\u7ffb\u8bd1] const \u662f\u5426\u4f1a\u5bf9\u7a0b\u5e8f…<\/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\/165047"}],"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=165047"}],"version-history":[{"count":1,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/165047\/revisions"}],"predecessor-version":[{"id":165049,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/165047\/revisions\/165049"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=165047"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=165047"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=165047"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}