{"id":170,"date":"2009-07-12T14:40:00","date_gmt":"2009-07-12T06:40:00","guid":{"rendered":"http:\/\/gsakd878.wordpress.com\/2009\/07\/12\/%e9%ab%98%e8%b4%a8%e9%87%8fc%e6%95%99%e7%a8%8b-%e7%ac%ac7%e7%ab%a0-%e5%86%85%e5%ad%98%e7%ae%a1%e7%90%86"},"modified":"2009-07-12T14:40:00","modified_gmt":"2009-07-12T06:40:00","slug":"%e9%ab%98%e8%b4%a8%e9%87%8fc%e6%95%99%e7%a8%8b-%e7%ac%ac7%e7%ab%a0-%e5%86%85%e5%ad%98%e7%ae%a1%e7%90%86","status":"publish","type":"post","link":"https:\/\/www.keyboardmeow.com\/?p=170","title":{"rendered":"\u9ad8\u8d28\u91cfC++\u6559\u7a0b — \u7b2c7\u7ae0 \u5185\u5b58\u7ba1\u7406"},"content":{"rendered":"
\u9ad8\u8d28\u91cfC++\u6559\u7a0b -- \u7b2c7\u7ae0 \u5185\u5b58\u7ba1\u7406<\/span><\/div>\n
\n\u6765\u6e90:www.vcworld.net<\/font><\/a>\u3000<\/div>\n
\n

\u6b22\u8fce\u8fdb\u5165\u5185\u5b58\u8fd9\u7247\u96f7\u533a\u3002\u4f1f\u5927\u7684Bill Gates
\n\u66fe\u7ecf\u5931\u8a00\uff1a<\/span><\/p>\n

640K ought to be enough for everybody<\/p>\n

\u2014 Bill Gates 1981<\/p>\n

\n\u7a0b\u5e8f\u5458\u4eec\u7ecf\u5e38\u7f16\u5199\u5185\u5b58\u7ba1\u7406\u7a0b\u5e8f\uff0c\u5f80\u5f80\u63d0\u5fc3\u540a\u80c6\u3002\u5982\u679c\u4e0d\u60f3\u89e6\u96f7\uff0c\u552f\u4e00\u7684\u89e3\u51b3\u529e\u6cd5\u5c31\u662f\u53d1\u73b0\u6240\u6709\u6f5c\u4f0f\u7684\u5730\u96f7\u5e76\u4e14\u6392\u9664\u5b83\u4eec\uff0c\u8eb2\u662f\u8eb2\u4e0d\u4e86\u7684\u3002\u672c\u7ae0\u7684\u5185\u5bb9\u6bd4\u4e00\u822c\u6559\u79d1\u4e66\u7684\u8981\u6df1\u5165\u5f97\u591a\uff0c\u8bfb\u8005\u9700\u7ec6\u5fc3\u9605\u8bfb\uff0c\u505a\u5230\u771f\u6b63\u5730\u901a\u6653\u5185\u5b58\u7ba1\u7406\u3002<\/p>\n

\u00a0<\/p>\n

7.1\u5185\u5b58\u5206\u914d\u65b9\u5f0f<\/font><\/strong><\/p>\n

\u5185\u5b58\u5206\u914d\u65b9\u5f0f\u6709\u4e09\u79cd\uff1a<\/p>\n

\uff081\uff09
\n\u4ece\u9759\u6001\u5b58\u50a8\u533a\u57df\u5206\u914d\u3002\u5185\u5b58\u5728\u7a0b\u5e8f\u7f16\u8bd1\u7684\u65f6\u5019\u5c31\u5df2\u7ecf\u5206\u914d\u597d\uff0c\u8fd9\u5757\u5185\u5b58\u5728\u7a0b\u5e8f\u7684\u6574\u4e2a\u8fd0\u884c\u671f\u95f4\u90fd\u5b58\u5728\u3002\u4f8b\u5982\u5168\u5c40\u53d8\u91cf\uff0cstatic\u53d8\u91cf\u3002<\/p>\n

\uff082\uff09
\n\u5728\u6808\u4e0a\u521b\u5efa\u3002\u5728\u6267\u884c\u51fd\u6570\u65f6\uff0c\u51fd\u6570\u5185\u5c40\u90e8\u53d8\u91cf\u7684\u5b58\u50a8\u5355\u5143\u90fd\u53ef\u4ee5\u5728\u6808\u4e0a\u521b\u5efa\uff0c\u51fd\u6570\u6267\u884c\u7ed3\u675f\u65f6\u8fd9\u4e9b\u5b58\u50a8\u5355\u5143\u81ea\u52a8\u88ab\u91ca\u653e\u3002\u6808\u5185\u5b58\u5206\u914d\u8fd0\u7b97\u5185\u7f6e\u4e8e\u5904\u7406\u5668\u7684\u6307\u4ee4\u96c6\u4e2d\uff0c\u6548\u7387\u5f88\u9ad8\uff0c\u4f46\u662f\u5206\u914d\u7684\u5185\u5b58\u5bb9\u91cf\u6709\u9650\u3002<\/p>\n

\uff083\uff09
\n\u4ece\u5806\u4e0a\u5206\u914d\uff0c\u4ea6\u79f0\u52a8\u6001\u5185\u5b58\u5206\u914d\u3002\u7a0b\u5e8f\u5728\u8fd0\u884c\u7684\u65f6\u5019\u7528malloc\u6216new\u7533\u8bf7\u4efb\u610f\u591a\u5c11\u7684\u5185\u5b58\uff0c\u7a0b\u5e8f\u5458\u81ea\u5df1\u8d1f\u8d23\u5728\u4f55\u65f6\u7528free\u6216delete\u91ca\u653e\u5185\u5b58\u3002\u52a8\u6001\u5185\u5b58\u7684\u751f\u5b58\u671f\u7531\u6211\u4eec\u51b3\u5b9a\uff0c\u4f7f\u7528\u975e\u5e38\u7075\u6d3b\uff0c\u4f46\u95ee\u9898\u4e5f\u6700\u591a\u3002<\/p>\n

\u00a0<\/p>\n

7.2\u5e38\u89c1\u7684\u5185\u5b58\u9519\u8bef\u53ca\u5176\u5bf9\u7b56<\/font><\/strong><\/p>\n

\n\u53d1\u751f\u5185\u5b58\u9519\u8bef\u662f\u4ef6\u975e\u5e38\u9ebb\u70e6\u7684\u4e8b\u60c5\u3002\u7f16\u8bd1\u5668\u4e0d\u80fd\u81ea\u52a8\u53d1\u73b0\u8fd9\u4e9b\u9519\u8bef\uff0c\u901a\u5e38\u662f\u5728\u7a0b\u5e8f\u8fd0\u884c\u65f6\u624d\u80fd\u6355\u6349\u5230\u3002\u800c\u8fd9\u4e9b\u9519\u8bef\u5927\u591a\u6ca1\u6709\u660e\u663e\u7684\u75c7\u72b6\uff0c\u65f6\u9690\u65f6\u73b0\uff0c\u589e\u52a0\u4e86\u6539\u9519\u7684\u96be\u5ea6\u3002\u6709\u65f6\u7528\u6237\u6012\u6c14\u51b2\u51b2\u5730\u628a\u4f60\u627e\u6765\uff0c\u7a0b\u5e8f\u5374\u6ca1\u6709\u53d1\u751f\u4efb\u4f55\u95ee\u9898\uff0c\u4f60\u4e00\u8d70\uff0c\u9519\u8bef\u53c8\u53d1\u4f5c\u4e86\u3002<\/p>\n

\u5e38\u89c1\u7684\u5185\u5b58\u9519\u8bef\u53ca\u5176\u5bf9\u7b56\u5982\u4e0b\uff1a<\/p>\n

\u5185\u5b58\u5206\u914d\u672a\u6210\u529f\uff0c\u5374\u4f7f\u7528\u4e86\u5b83\u3002<\/p>\n

\n\u7f16\u7a0b\u65b0\u624b\u5e38\u72af\u8fd9\u79cd\u9519\u8bef\uff0c\u56e0\u4e3a\u4ed6\u4eec\u6ca1\u6709\u610f\u8bc6\u5230\u5185\u5b58\u5206\u914d\u4f1a\u4e0d\u6210\u529f\u3002\u5e38\u7528\u89e3\u51b3\u529e\u6cd5\u662f\uff0c\u5728\u4f7f\u7528\u5185\u5b58\u4e4b\u524d\u68c0\u67e5\u6307\u9488\u662f\u5426\u4e3aNULL\u3002\u5982\u679c\u6307\u9488p\u662f\u51fd\u6570\u7684\u53c2\u6570\uff0c\u90a3\u4e48\u5728\u51fd\u6570\u7684\u5165\u53e3\u5904\u7528assert(p!=NULL)\u8fdb\u884c\u68c0\u67e5\u3002\u5982\u679c\u662f\u7528malloc\u6216new\u6765\u7533\u8bf7\u5185\u5b58\uff0c\u5e94\u8be5\u7528if(p==NULL)
\n\u6216if(p!=NULL)\u8fdb\u884c\u9632\u9519\u5904\u7406\u3002<\/p>\n

\u25c6\u5185\u5b58\u5206\u914d\u867d\u7136\u6210\u529f\uff0c\u4f46\u662f\u5c1a\u672a\u521d\u59cb\u5316\u5c31\u5f15\u7528\u5b83\u3002<\/p>\n

\u72af\u8fd9\u79cd\u9519\u8bef\u4e3b\u8981\u6709\u4e24\u4e2a\u8d77\u56e0\uff1a\u4e00\u662f\u6ca1\u6709\u521d\u59cb\u5316\u7684\u89c2\u5ff5\uff1b\u4e8c\u662f\u8bef\u4ee5\u4e3a\u5185\u5b58\u7684\u7f3a\u7701\u521d\u503c\u5168\u4e3a\u96f6\uff0c\u5bfc\u81f4\u5f15\u7528\u521d\u503c\u9519\u8bef\uff08\u4f8b\u5982\u6570\u7ec4\uff09\u3002<\/p>\n

\n\u5185\u5b58\u7684\u7f3a\u7701\u521d\u503c\u7a76\u7adf\u662f\u4ec0\u4e48\u5e76\u6ca1\u6709\u7edf\u4e00\u7684\u6807\u51c6\uff0c\u5c3d\u7ba1\u6709\u4e9b\u65f6\u5019\u4e3a\u96f6\u503c\uff0c\u6211\u4eec\u5b81\u53ef\u4fe1\u5176\u65e0\u4e0d\u53ef\u4fe1\u5176\u6709\u3002\u6240\u4ee5\u65e0\u8bba\u7528\u4f55\u79cd\u65b9\u5f0f\u521b\u5efa\u6570\u7ec4\uff0c\u90fd\u522b\u5fd8\u4e86\u8d4b\u521d\u503c\uff0c\u5373\u4fbf\u662f\u8d4b\u96f6\u503c\u4e5f\u4e0d\u53ef\u7701\u7565\uff0c\u4e0d\u8981\u5acc\u9ebb\u70e6\u3002<\/p>\n

\u25c6\u5185\u5b58\u5206\u914d\u6210\u529f\u5e76\u4e14\u5df2\u7ecf\u521d\u59cb\u5316\uff0c\u4f46\u64cd\u4f5c\u8d8a\u8fc7\u4e86\u5185\u5b58\u7684\u8fb9\u754c\u3002<\/p>\n

\u4f8b\u5982\u5728\u4f7f\u7528\u6570\u7ec4\u65f6\u7ecf\u5e38\u53d1\u751f\u4e0b\u6807\u201c\u591a1\u201d\u6216\u8005\u201c\u5c111\u201d\u7684\u64cd\u4f5c\u3002\u7279\u522b\u662f\u5728for\u5faa\u73af\u8bed\u53e5\u4e2d\uff0c\u5faa\u73af\u6b21\u6570\u5f88\u5bb9\u6613\u641e\u9519\uff0c\u5bfc\u81f4\u6570\u7ec4\u64cd\u4f5c\u8d8a\u754c\u3002<\/p>\n

\u25c6\u5fd8\u8bb0\u4e86\u91ca\u653e\u5185\u5b58\uff0c\u9020\u6210\u5185\u5b58\u6cc4\u9732\u3002<\/p>\n

\n\u542b\u6709\u8fd9\u79cd\u9519\u8bef\u7684\u51fd\u6570\u6bcf\u88ab\u8c03\u7528\u4e00\u6b21\u5c31\u4e22\u5931\u4e00\u5757\u5185\u5b58\u3002\u521a\u5f00\u59cb\u65f6\u7cfb\u7edf\u7684\u5185\u5b58\u5145\u8db3\uff0c\u4f60\u770b\u4e0d\u5230\u9519\u8bef\u3002\u7ec8\u6709\u4e00\u6b21\u7a0b\u5e8f\u7a81\u7136\u6b7b\u6389\uff0c\u7cfb\u7edf\u51fa\u73b0\u63d0\u793a\uff1a\u5185\u5b58\u8017\u5c3d\u3002<\/p>\n

\n\u52a8\u6001\u5185\u5b58\u7684\u7533\u8bf7\u4e0e\u91ca\u653e\u5fc5\u987b\u914d\u5bf9\uff0c\u7a0b\u5e8f\u4e2dmalloc\u4e0efree\u7684\u4f7f\u7528\u6b21\u6570\u4e00\u5b9a\u8981\u76f8\u540c\uff0c\u5426\u5219\u80af\u5b9a\u6709\u9519\u8bef\uff08new\/delete\u540c\u7406\uff09\u3002<\/p>\n

\u00a0<\/p>\n

\u25c6\u91ca\u653e\u4e86\u5185\u5b58\u5374\u7ee7\u7eed\u4f7f\u7528\u5b83\u3002<\/p>\n

\u6709\u4e09\u79cd\u60c5\u51b5\uff1a<\/p>\n

\n\uff081\uff09\u7a0b\u5e8f\u4e2d\u7684\u5bf9\u8c61\u8c03\u7528\u5173\u7cfb\u8fc7\u4e8e\u590d\u6742\uff0c\u5b9e\u5728\u96be\u4ee5\u641e\u6e05\u695a\u67d0\u4e2a\u5bf9\u8c61\u7a76\u7adf\u662f\u5426\u5df2\u7ecf\u91ca\u653e\u4e86\u5185\u5b58\uff0c\u6b64\u65f6\u5e94\u8be5\u91cd\u65b0\u8bbe\u8ba1\u6570\u636e\u7ed3\u6784\uff0c\u4ece\u6839\u672c\u4e0a\u89e3\u51b3\u5bf9\u8c61\u7ba1\u7406\u7684\u6df7\u4e71\u5c40\u9762\u3002<\/p>\n

\n\uff082\uff09\u51fd\u6570\u7684return\u8bed\u53e5\u5199\u9519\u4e86\uff0c\u6ce8\u610f\u4e0d\u8981\u8fd4\u56de\u6307\u5411\u201c\u6808\u5185\u5b58\u201d\u7684\u201c\u6307\u9488\u201d\u6216\u8005\u201c\u5f15\u7528\u201d\uff0c\u56e0\u4e3a\u8be5\u5185\u5b58\u5728\u51fd\u6570\u4f53\u7ed3\u675f\u65f6\u88ab\u81ea\u52a8\u9500\u6bc1\u3002<\/p>\n

\uff083\uff09\u4f7f\u7528free\u6216delete\u91ca\u653e\u4e86\u5185\u5b58\u540e\uff0c\u6ca1\u6709\u5c06\u6307\u9488\u8bbe\u7f6e\u4e3aNULL\u3002\u5bfc\u81f4\u4ea7\u751f\u201c\u91ce\u6307\u9488\u201d\u3002<\/p>\n

\u00a0<\/p>\n

\n\u25cf\u3010\u89c4\u52197-2-1\u3011\u7528malloc\u6216new\u7533\u8bf7\u5185\u5b58\u4e4b\u540e\uff0c\u5e94\u8be5\u7acb\u5373\u68c0\u67e5\u6307\u9488\u503c\u662f\u5426\u4e3aNULL\u3002\u9632\u6b62\u4f7f\u7528\u6307\u9488\u503c\u4e3aNULL\u7684\u5185\u5b58\u3002<\/p>\n

\u25cf\u3010\u89c4\u52197-2-2\u3011\u4e0d\u8981\u5fd8\u8bb0\u4e3a\u6570\u7ec4\u548c\u52a8\u6001\u5185\u5b58\u8d4b\u521d\u503c\u3002\u9632\u6b62\u5c06\u672a\u88ab\u521d\u59cb\u5316\u7684\u5185\u5b58\u4f5c\u4e3a\u53f3\u503c\u4f7f\u7528\u3002<\/p>\n

\u25cf\u3010\u89c4\u52197-2-3\u3011\u907f\u514d\u6570\u7ec4\u6216\u6307\u9488\u7684\u4e0b\u6807\u8d8a\u754c\uff0c\u7279\u522b\u8981\u5f53\u5fc3\u53d1\u751f\u201c\u591a1\u201d\u6216\u8005\u201c\u5c111\u201d\u64cd\u4f5c\u3002<\/p>\n

\u25cf\u3010\u89c4\u52197-2-4\u3011\u52a8\u6001\u5185\u5b58\u7684\u7533\u8bf7\u4e0e\u91ca\u653e\u5fc5\u987b\u914d\u5bf9\uff0c\u9632\u6b62\u5185\u5b58\u6cc4\u6f0f\u3002<\/p>\n

\u25cf\u3010\u89c4\u52197-2-5\u3011\u7528free\u6216delete\u91ca\u653e\u4e86\u5185\u5b58\u4e4b\u540e\uff0c\u7acb\u5373\u5c06\u6307\u9488\u8bbe\u7f6e\u4e3aNULL\uff0c\u9632\u6b62\u4ea7\u751f\u201c\u91ce\u6307\u9488\u201d\u3002<\/p>\n

\u00a0<\/p>\n

7.3\u6307\u9488\u4e0e\u6570\u7ec4\u7684\u5bf9\u6bd4<\/font><\/strong><\/p>\n

C++\/C\u7a0b\u5e8f\u4e2d\uff0c\u6307\u9488\u548c\u6570\u7ec4\u5728\u4e0d\u5c11\u5730\u65b9\u53ef\u4ee5\u76f8\u4e92\u66ff\u6362\u7740\u7528\uff0c\u8ba9\u4eba\u4ea7\u751f\u4e00\u79cd\u9519\u89c9\uff0c\u4ee5\u4e3a\u4e24\u8005\u662f\u7b49\u4ef7\u7684\u3002<\/p>\n

\n\u6570\u7ec4\u8981\u4e48\u5728\u9759\u6001\u5b58\u50a8\u533a\u88ab\u521b\u5efa\uff08\u5982\u5168\u5c40\u6570\u7ec4\uff09\uff0c\u8981\u4e48\u5728\u6808\u4e0a\u88ab\u521b\u5efa\u3002\u6570\u7ec4\u540d\u5bf9\u5e94\u7740\uff08\u800c\u4e0d\u662f\u6307\u5411\uff09\u4e00\u5757\u5185\u5b58\uff0c\u5176\u5730\u5740\u4e0e\u5bb9\u91cf\u5728\u751f\u547d\u671f\u5185\u4fdd\u6301\u4e0d\u53d8\uff0c\u53ea\u6709\u6570\u7ec4\u7684\u5185\u5bb9\u53ef\u4ee5\u6539\u53d8\u3002<\/p>\n

\u6307\u9488\u53ef\u4ee5\u968f\u65f6\u6307\u5411\u4efb\u610f\u7c7b\u578b\u7684\u5185\u5b58\u5757\uff0c\u5b83\u7684\u7279\u5f81\u662f\u201c\u53ef\u53d8\u201d\uff0c\u6240\u4ee5\u6211\u4eec\u5e38\u7528\u6307\u9488\u6765\u64cd\u4f5c\u52a8\u6001\u5185\u5b58\u3002\u6307\u9488\u8fdc\u6bd4\u6570\u7ec4\u7075\u6d3b\uff0c\u4f46\u4e5f\u66f4\u5371\u9669\u3002<\/p>\n

\u4e0b\u9762\u4ee5\u5b57\u7b26\u4e32\u4e3a\u4f8b\u6bd4\u8f83\u6307\u9488\u4e0e\u6570\u7ec4\u7684\u7279\u6027\u3002<\/p>\n

\u00a0<\/p>\n

7.3.1 \u4fee\u6539\u5185\u5bb9<\/strong><\/p>\n

\u793a\u4f8b7-3-1\u4e2d\uff0c\u5b57\u7b26\u6570\u7ec4a\u7684\u5bb9\u91cf\u662f6\u4e2a\u5b57\u7b26\uff0c\u5176\u5185\u5bb9\u4e3ahello\u3002a\u7684\u5185\u5bb9\u53ef\u4ee5\u6539\u53d8\uff0c\u5982a[0]=
\n\u2018X\u2019\u3002\u6307\u9488p\u6307\u5411\u5e38\u91cf\u5b57\u7b26\u4e32\u201cworld\u201d\uff08\u4f4d\u4e8e\u9759\u6001\u5b58\u50a8\u533a\uff0c\u5185\u5bb9\u4e3aworld\uff09\uff0c\u5e38\u91cf\u5b57\u7b26\u4e32\u7684\u5185\u5bb9\u662f\u4e0d\u53ef\u4ee5\u88ab\u4fee\u6539\u7684\u3002\u4ece\u8bed\u6cd5\u4e0a\u770b\uff0c\u7f16\u8bd1\u5668\u5e76\u4e0d\u89c9\u5f97\u8bed\u53e5p[0]=
\n\u2018X\u2019\u6709\u4ec0\u4e48\u4e0d\u59a5\uff0c\u4f46\u662f\u8be5\u8bed\u53e5\u4f01\u56fe\u4fee\u6539\u5e38\u91cf\u5b57\u7b26\u4e32\u7684\u5185\u5bb9\u800c\u5bfc\u81f4\u8fd0\u884c\u9519\u8bef\u3002<\/p>\n\n\n\n
\n

char a[] = \u201chello\u201d;<\/p>\n

a[0] = \u2018X\u2019;<\/p>\n

cout << a
\n<< endl;<\/p>\n

char *p = \u201cworld\u201d; \/\/ \u6ce8\u610fp\u6307\u5411\u5e38\u91cf\u5b57\u7b26\u4e32<\/p>\n

p[0] = \u2018X\u2019; \/\/ \u7f16\u8bd1\u5668\u4e0d\u80fd\u53d1\u73b0\u8be5\u9519\u8bef<\/p>\n

cout << p
\n<< endl;<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-3-1 \u4fee\u6539\u6570\u7ec4\u548c\u6307\u9488\u7684\u5185\u5bb9<\/p>\n

\u00a0<\/p>\n

7.3.2 \u5185\u5bb9\u590d\u5236\u4e0e\u6bd4\u8f83<\/strong><\/p>\n

\u4e0d\u80fd\u5bf9\u6570\u7ec4\u540d\u8fdb\u884c\u76f4\u63a5\u590d\u5236\u4e0e\u6bd4\u8f83\u3002\u793a\u4f8b7-3-2\u4e2d\uff0c\u82e5\u60f3\u628a\u6570\u7ec4a\u7684\u5185\u5bb9\u590d\u5236\u7ed9\u6570\u7ec4b\uff0c\u4e0d\u80fd\u7528\u8bed\u53e5 b = a
\n\uff0c\u5426\u5219\u5c06\u4ea7\u751f\u7f16\u8bd1\u9519\u8bef\u3002\u5e94\u8be5\u7528\u6807\u51c6\u5e93\u51fd\u6570strcpy\u8fdb\u884c\u590d\u5236\u3002\u540c\u7406\uff0c\u6bd4\u8f83b\u548ca\u7684\u5185\u5bb9\u662f\u5426\u76f8\u540c\uff0c\u4e0d\u80fd\u7528if(b==a)
\n\u6765\u5224\u65ad\uff0c\u5e94\u8be5\u7528\u6807\u51c6\u5e93\u51fd\u6570strcmp\u8fdb\u884c\u6bd4\u8f83\u3002<\/p>\n

\u8bed\u53e5p = a
\n\u5e76\u4e0d\u80fd\u628aa\u7684\u5185\u5bb9\u590d\u5236\u6307\u9488p\uff0c\u800c\u662f\u628aa\u7684\u5730\u5740\u8d4b\u7ed9\u4e86p\u3002\u8981\u60f3\u590d\u5236a\u7684\u5185\u5bb9\uff0c\u53ef\u4ee5\u5148\u7528\u5e93\u51fd\u6570malloc\u4e3ap\u7533\u8bf7\u4e00\u5757\u5bb9\u91cf\u4e3astrlen(a)+1\u4e2a\u5b57\u7b26\u7684\u5185\u5b58\uff0c\u518d\u7528strcpy\u8fdb\u884c\u5b57\u7b26\u4e32\u590d\u5236\u3002\u540c\u7406\uff0c\u8bed\u53e5if(p==a)
\n\u6bd4\u8f83\u7684\u4e0d\u662f\u5185\u5bb9\u800c\u662f\u5730\u5740\uff0c\u5e94\u8be5\u7528\u5e93\u51fd\u6570strcmp\u6765\u6bd4\u8f83\u3002<\/p>\n\n\n\n\n
\n

\/\/ \u6570\u7ec4\u2026<\/p>\n

char a[] = \"hello\";<\/p>\n

char b[10];<\/p>\n

strcpy(b, a); \/\/ \u4e0d\u80fd\u7528 b = a;<\/p>\n

if(strcmp(b, a) == 0) \/\/ \u4e0d\u80fd\u7528 if (b == a)<\/p>\n

\u2026<\/p>\n<\/td>\n<\/tr>\n

\n

\/\/ \u6307\u9488\u2026<\/p>\n

int len = strlen(a);<\/p>\n

char *p = (char *)malloc(sizeof(char)*(len+1));<\/p>\n

strcpy(p,a); \/\/ \u4e0d\u8981\u7528 p = a;<\/p>\n

if(strcmp(p, a) == 0) \/\/ \u4e0d\u8981\u7528 if (p == a)<\/p>\n

\u2026<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-3-2 \u6570\u7ec4\u548c\u6307\u9488\u7684\u5185\u5bb9\u590d\u5236\u4e0e\u6bd4\u8f83<\/p>\n

\u00a0<\/p>\n

7.3.3 \u8ba1\u7b97\u5185\u5b58\u5bb9\u91cf<\/strong><\/p>\n

\n\u7528\u8fd0\u7b97\u7b26sizeof\u53ef\u4ee5\u8ba1\u7b97\u51fa\u6570\u7ec4\u7684\u5bb9\u91cf\uff08\u5b57\u8282\u6570\uff09\u3002\u793a\u4f8b7-3-3\uff08a\uff09\u4e2d\uff0csizeof(a)\u7684\u503c\u662f12\uff08\u6ce8\u610f\u522b\u5fd8\u4e86\u2019\u2019\uff09\u3002\u6307\u9488p\u6307\u5411a\uff0c\u4f46\u662fsizeof(p)\u7684\u503c\u5374\u662f4\u3002\u8fd9\u662f\u56e0\u4e3asizeof(p)\u5f97\u5230\u7684\u662f\u4e00\u4e2a\u6307\u9488\u53d8\u91cf\u7684\u5b57\u8282\u6570\uff0c\u76f8\u5f53\u4e8esizeof(char*)\uff0c\u800c\u4e0d\u662fp\u6240\u6307\u7684\u5185\u5b58\u5bb9\u91cf\u3002C++\/C\u8bed\u8a00\u6ca1\u6709\u529e\u6cd5\u77e5\u9053\u6307\u9488\u6240\u6307\u7684\u5185\u5b58\u5bb9\u91cf\uff0c\u9664\u975e\u5728\u7533\u8bf7\u5185\u5b58\u65f6\u8bb0\u4f4f\u5b83\u3002<\/p>\n

\n\u6ce8\u610f\u5f53\u6570\u7ec4\u4f5c\u4e3a\u51fd\u6570\u7684\u53c2\u6570\u8fdb\u884c\u4f20\u9012\u65f6\uff0c\u8be5\u6570\u7ec4\u81ea\u52a8\u9000\u5316\u4e3a\u540c\u7c7b\u578b\u7684\u6307\u9488\u3002\u793a\u4f8b7-3-3\uff08b\uff09\u4e2d\uff0c\u4e0d\u8bba\u6570\u7ec4a\u7684\u5bb9\u91cf\u662f\u591a\u5c11\uff0csizeof(a)\u59cb\u7ec8\u7b49\u4e8esizeof(char
\n*)\u3002<\/p>\n\n\n\n
\n

char a[] = \"hello world\";<\/p>\n

char *p = a;<\/p>\n

cout<< sizeof(a)
\n<< endl; \/\/ 12\u5b57\u8282<\/p>\n

cout<< sizeof(p)
\n<< endl; \/\/ 4\u5b57\u8282<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-3-3\uff08a\uff09 \u8ba1\u7b97\u6570\u7ec4\u548c\u6307\u9488\u7684\u5185\u5b58\u5bb9\u91cf<\/p>\n\n\n\n
\n

void Func(char a[100])<\/p>\n

{<\/p>\n

cout<< sizeof(a)
\n<< endl; \/\/ 4\u5b57\u8282\u800c\u4e0d\u662f100\u5b57\u8282<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-3-3\uff08b\uff09 \u6570\u7ec4\u9000\u5316\u4e3a\u6307\u9488<\/p>\n

\u00a0<\/p>\n

7.4\u6307\u9488\u53c2\u6570\u662f\u5982\u4f55\u4f20\u9012\u5185\u5b58\u7684\uff1f<\/font><\/strong><\/p>\n

\u5982\u679c\u51fd\u6570\u7684\u53c2\u6570\u662f\u4e00\u4e2a\u6307\u9488\uff0c\u4e0d\u8981\u6307\u671b\u7528\u8be5\u6307\u9488\u53bb\u7533\u8bf7\u52a8\u6001\u5185\u5b58\u3002\u793a\u4f8b7-4-1\u4e2d\uff0cTest\u51fd\u6570\u7684\u8bed\u53e5GetMemory(str,
\n200)\u5e76\u6ca1\u6709\u4f7fstr\u83b7\u5f97\u671f\u671b\u7684\u5185\u5b58\uff0cstr\u4f9d\u65e7\u662fNULL\uff0c\u4e3a\u4ec0\u4e48\uff1f<\/p>\n\n\n\n\n
\n

void GetMemory(char *p, int num)<\/p>\n

{<\/p>\n

p = (char *)malloc(sizeof(char) * num);<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void Test(void)<\/p>\n

{<\/p>\n

char *str = NULL;<\/p>\n

GetMemory(str, 100); \/\/ str \u4ecd\u7136\u4e3a NULL<\/p>\n

strcpy(str, \"hello\"); \/\/ \u8fd0\u884c\u9519\u8bef<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-4-1 \u8bd5\u56fe\u7528\u6307\u9488\u53c2\u6570\u7533\u8bf7\u52a8\u6001\u5185\u5b58<\/p>\n

\u6bdb\u75c5\u51fa\u5728\u51fd\u6570GetMemory\u4e2d\u3002\u7f16\u8bd1\u5668\u603b\u662f\u8981\u4e3a\u51fd\u6570\u7684\u6bcf\u4e2a\u53c2\u6570\u5236\u4f5c\u4e34\u65f6\u526f\u672c\uff0c\u6307\u9488\u53c2\u6570p\u7684\u526f\u672c\u662f _p\uff0c\u7f16\u8bd1\u5668\u4f7f _p =
\np\u3002\u5982\u679c\u51fd\u6570\u4f53\u5185\u7684\u7a0b\u5e8f\u4fee\u6539\u4e86_p\u7684\u5185\u5bb9\uff0c\u5c31\u5bfc\u81f4\u53c2\u6570p\u7684\u5185\u5bb9\u4f5c\u76f8\u5e94\u7684\u4fee\u6539\u3002\u8fd9\u5c31\u662f\u6307\u9488\u53ef\u4ee5\u7528\u4f5c\u8f93\u51fa\u53c2\u6570\u7684\u539f\u56e0\u3002\u5728\u672c\u4f8b\u4e2d\uff0c_p\u7533\u8bf7\u4e86\u65b0\u7684\u5185\u5b58\uff0c\u53ea\u662f\u628a_p\u6240\u6307\u7684\u5185\u5b58\u5730\u5740\u6539\u53d8\u4e86\uff0c\u4f46\u662fp\u4e1d\u6beb\u672a\u53d8\u3002\u6240\u4ee5\u51fd\u6570GetMemory\u5e76\u4e0d\u80fd\u8f93\u51fa\u4efb\u4f55\u4e1c\u897f\u3002\u4e8b\u5b9e\u4e0a\uff0c\u6bcf\u6267\u884c\u4e00\u6b21GetMemory\u5c31\u4f1a\u6cc4\u9732\u4e00\u5757\u5185\u5b58\uff0c\u56e0\u4e3a\u6ca1\u6709\u7528free\u91ca\u653e\u5185\u5b58\u3002<\/p>\n

\u5982\u679c\u975e\u5f97\u8981\u7528\u6307\u9488\u53c2\u6570\u53bb\u7533\u8bf7\u5185\u5b58\uff0c\u90a3\u4e48\u5e94\u8be5\u6539\u7528\u201c\u6307\u5411\u6307\u9488\u7684\u6307\u9488\u201d\uff0c\u89c1\u793a\u4f8b7-4-2\u3002<\/p>\n\n\n\n\n
\n

void GetMemory2(char **p, int num)<\/p>\n

{<\/p>\n

*p = (char *)malloc(sizeof(char) * num);<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void Test2(void)<\/p>\n

{<\/p>\n

char *str = NULL;<\/p>\n

GetMemory2(&str, 100); \/\/ \u6ce8\u610f\u53c2\u6570\u662f
\n&str\uff0c\u800c\u4e0d\u662fstr<\/p>\n

strcpy(str, \"hello\");<\/p>\n

cout<< str
\n<< endl;<\/p>\n

free(str);<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-4-2\u7528\u6307\u5411\u6307\u9488\u7684\u6307\u9488\u7533\u8bf7\u52a8\u6001\u5185\u5b58<\/p>\n

\u00a0<\/p>\n

\u7531\u4e8e\u201c\u6307\u5411\u6307\u9488\u7684\u6307\u9488\u201d\u8fd9\u4e2a\u6982\u5ff5\u4e0d\u5bb9\u6613\u7406\u89e3\uff0c\u6211\u4eec\u53ef\u4ee5\u7528\u51fd\u6570\u8fd4\u56de\u503c\u6765\u4f20\u9012\u52a8\u6001\u5185\u5b58\u3002\u8fd9\u79cd\u65b9\u6cd5\u66f4\u52a0\u7b80\u5355\uff0c\u89c1\u793a\u4f8b7-4-3\u3002<\/p>\n\n\n\n\n
\n

char *GetMemory3(int num)<\/p>\n

{<\/p>\n

char *p = (char *)malloc(sizeof(char) * num);<\/p>\n

return p;<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void Test3(void)<\/p>\n

{<\/p>\n

char *str = NULL;<\/p>\n

str = GetMemory3(100);<\/p>\n

strcpy(str, \"hello\");<\/p>\n

cout<< str
\n<< endl;<\/p>\n

free(str);<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-4-3 \u7528\u51fd\u6570\u8fd4\u56de\u503c\u6765\u4f20\u9012\u52a8\u6001\u5185\u5b58<\/p>\n

\n\u7528\u51fd\u6570\u8fd4\u56de\u503c\u6765\u4f20\u9012\u52a8\u6001\u5185\u5b58\u8fd9\u79cd\u65b9\u6cd5\u867d\u7136\u597d\u7528\uff0c\u4f46\u662f\u5e38\u5e38\u6709\u4eba\u628areturn\u8bed\u53e5\u7528\u9519\u4e86\u3002\u8fd9\u91cc\u5f3a\u8c03\u4e0d\u8981\u7528return\u8bed\u53e5\u8fd4\u56de\u6307\u5411\u201c\u6808\u5185\u5b58\u201d\u7684\u6307\u9488\uff0c\u56e0\u4e3a\u8be5\u5185\u5b58\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u81ea\u52a8\u6d88\u4ea1\uff0c\u89c1\u793a\u4f8b7-4-4\u3002<\/p>\n\n\n\n\n
\n

char *GetString(void)<\/p>\n

{<\/p>\n

char p[] = \"hello world\";<\/p>\n

return p; \/\/ \u7f16\u8bd1\u5668\u5c06\u63d0\u51fa\u8b66\u544a<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void Test4(void)<\/p>\n

{<\/p>\n

char *str = NULL;<\/p>\n

str = GetString(); \/\/ str \u7684\u5185\u5bb9\u662f\u5783\u573e<\/p>\n

cout<< str
\n<< endl;<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-4-4 return\u8bed\u53e5\u8fd4\u56de\u6307\u5411\u201c\u6808\u5185\u5b58\u201d\u7684\u6307\u9488<\/p>\n

\u7528\u8c03\u8bd5\u5668\u9010\u6b65\u8ddf\u8e2aTest4\uff0c\u53d1\u73b0\u6267\u884cstr =
\nGetString\u8bed\u53e5\u540estr\u4e0d\u518d\u662fNULL\u6307\u9488\uff0c\u4f46\u662fstr\u7684\u5185\u5bb9\u4e0d\u662f\u201chello world\u201d\u800c\u662f\u5783\u573e\u3002<\/p>\n

\u5982\u679c\u628a\u793a\u4f8b7-4-4\u6539\u5199\u6210\u793a\u4f8b7-4-5\uff0c\u4f1a\u600e\u4e48\u6837\uff1f<\/p>\n\n\n\n\n
\n

char *GetString2(void)<\/p>\n

{<\/p>\n

char *p = \"hello world\";<\/p>\n

return p;<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void Test5(void)<\/p>\n

{<\/p>\n

char *str = NULL;<\/p>\n

str = GetString2();<\/p>\n

cout<< str
\n<< endl;<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-4-5 return\u8bed\u53e5\u8fd4\u56de\u5e38\u91cf\u5b57\u7b26\u4e32<\/p>\n

\u51fd\u6570Test5\u8fd0\u884c\u867d\u7136\u4e0d\u4f1a\u51fa\u9519\uff0c\u4f46\u662f\u51fd\u6570GetString2\u7684\u8bbe\u8ba1\u6982\u5ff5\u5374\u662f\u9519\u8bef\u7684\u3002\u56e0\u4e3aGetString2\u5185\u7684\u201chello
\nworld\u201d\u662f\u5e38\u91cf\u5b57\u7b26\u4e32\uff0c\u4f4d\u4e8e\u9759\u6001\u5b58\u50a8\u533a\uff0c\u5b83\u5728\u7a0b\u5e8f\u751f\u547d\u671f\u5185\u6052\u5b9a\u4e0d\u53d8\u3002\u65e0\u8bba\u4ec0\u4e48\u65f6\u5019\u8c03\u7528GetString2\uff0c\u5b83\u8fd4\u56de\u7684\u59cb\u7ec8\u662f\u540c\u4e00\u4e2a\u201c\u53ea\u8bfb\u201d\u7684\u5185\u5b58\u5757\u3002<\/p>\n

\u00a0<\/p>\n

7.5
\nfree\u548cdelete\u628a\u6307\u9488\u600e\u4e48\u5566\uff1f<\/font><\/strong><\/p>\n

\n\u522b\u770bfree\u548cdelete\u7684\u540d\u5b57\u6076\u72e0\u72e0\u7684\uff08\u5c24\u5176\u662fdelete\uff09\uff0c\u5b83\u4eec\u53ea\u662f\u628a\u6307\u9488\u6240\u6307\u7684\u5185\u5b58\u7ed9\u91ca\u653e\u6389\uff0c\u4f46\u5e76\u6ca1\u6709\u628a\u6307\u9488\u672c\u8eab\u5e72\u6389\u3002<\/p>\n

\n\u7528\u8c03\u8bd5\u5668\u8ddf\u8e2a\u793a\u4f8b7-5\uff0c\u53d1\u73b0\u6307\u9488p\u88abfree\u4ee5\u540e\u5176\u5730\u5740\u4ecd\u7136\u4e0d\u53d8\uff08\u975eNULL\uff09\uff0c\u53ea\u662f\u8be5\u5730\u5740\u5bf9\u5e94\u7684\u5185\u5b58\u662f\u5783\u573e\uff0cp\u6210\u4e86\u201c\u91ce\u6307\u9488\u201d\u3002\u5982\u679c\u6b64\u65f6\u4e0d\u628ap\u8bbe\u7f6e\u4e3aNULL\uff0c\u4f1a\u8ba9\u4eba\u8bef\u4ee5\u4e3ap\u662f\u4e2a\u5408\u6cd5\u7684\u6307\u9488\u3002<\/p>\n

\u5982\u679c\u7a0b\u5e8f\u6bd4\u8f83\u957f\uff0c\u6211\u4eec\u6709\u65f6\u8bb0\u4e0d\u4f4fp\u6240\u6307\u7684\u5185\u5b58\u662f\u5426\u5df2\u7ecf\u88ab\u91ca\u653e\uff0c\u5728\u7ee7\u7eed\u4f7f\u7528p\u4e4b\u524d\uff0c\u901a\u5e38\u4f1a\u7528\u8bed\u53e5if (p !=
\nNULL)\u8fdb\u884c\u9632\u9519\u5904\u7406\u3002\u5f88\u9057\u61be\uff0c\u6b64\u65f6if\u8bed\u53e5\u8d77\u4e0d\u5230\u9632\u9519\u4f5c\u7528\uff0c\u56e0\u4e3a\u5373\u4fbfp\u4e0d\u662fNULL\u6307\u9488\uff0c\u5b83\u4e5f\u4e0d\u6307\u5411\u5408\u6cd5\u7684\u5185\u5b58\u5757\u3002<\/p>\n\n\n\n
\n

char *p = (char *) malloc(100);<\/p>\n

strcpy(p, \u201chello\u201d);<\/p>\n

free(p); \/\/ p \u6240\u6307\u7684\u5185\u5b58\u88ab\u91ca\u653e\uff0c\u4f46\u662fp\u6240\u6307\u7684\u5730\u5740\u4ecd\u7136\u4e0d\u53d8<\/p>\n

\u2026<\/p>\n

if(p != NULL) \/\/ \u6ca1\u6709\u8d77\u5230\u9632\u9519\u4f5c\u7528<\/p>\n

{<\/p>\n

strcpy(p, \u201cworld\u201d); \/\/ \u51fa\u9519<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-5 p\u6210\u4e3a\u91ce\u6307\u9488<\/p>\n

\u00a0<\/p>\n

7.6 \u52a8\u6001\u5185\u5b58\u4f1a\u88ab\u81ea\u52a8\u91ca\u653e\u5417\uff1f<\/font><\/strong><\/p>\n

\n\u51fd\u6570\u4f53\u5185\u7684\u5c40\u90e8\u53d8\u91cf\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u81ea\u52a8\u6d88\u4ea1\u3002\u5f88\u591a\u4eba\u8bef\u4ee5\u4e3a\u793a\u4f8b7-6\u662f\u6b63\u786e\u7684\u3002\u7406\u7531\u662fp\u662f\u5c40\u90e8\u7684\u6307\u9488\u53d8\u91cf\uff0c\u5b83\u6d88\u4ea1\u7684\u65f6\u5019\u4f1a\u8ba9\u5b83\u6240\u6307\u7684\u52a8\u6001\u5185\u5b58\u4e00\u8d77\u5b8c\u86cb\u3002\u8fd9\u662f\u9519\u89c9\uff01<\/p>\n\n\n\n
\n

void Func(void)<\/p>\n

{<\/p>\n

char *p = (char *) malloc(100); \/\/ \u52a8\u6001\u5185\u5b58\u4f1a\u81ea\u52a8\u91ca\u653e\u5417\uff1f<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-6 \u8bd5\u56fe\u8ba9\u52a8\u6001\u5185\u5b58\u81ea\u52a8\u91ca\u653e<\/p>\n

\u6211\u4eec\u53d1\u73b0\u6307\u9488\u6709\u4e00\u4e9b\u201c\u4f3c\u662f\u800c\u975e\u201d\u7684\u7279\u5f81\uff1a<\/p>\n

\uff081\uff09\u6307\u9488\u6d88\u4ea1\u4e86\uff0c\u5e76\u4e0d\u8868\u793a\u5b83\u6240\u6307\u7684\u5185\u5b58\u4f1a\u88ab\u81ea\u52a8\u91ca\u653e\u3002<\/p>\n

\uff082\uff09\u5185\u5b58\u88ab\u91ca\u653e\u4e86\uff0c\u5e76\u4e0d\u8868\u793a\u6307\u9488\u4f1a\u6d88\u4ea1\u6216\u8005\u6210\u4e86NULL\u6307\u9488\u3002<\/p>\n

\u8fd9\u8868\u660e\u91ca\u653e\u5185\u5b58\u5e76\u4e0d\u662f\u4e00\u4ef6\u53ef\u4ee5\u8349\u7387\u5bf9\u5f85\u7684\u4e8b\u3002\u4e5f\u8bb8\u6709\u4eba\u4e0d\u670d\u6c14\uff0c\u4e00\u5b9a\u8981\u627e\u51fa\u53ef\u4ee5\u8349\u7387\u884c\u4e8b\u7684\u7406\u7531\uff1a<\/p>\n

\n\u5982\u679c\u7a0b\u5e8f\u7ec8\u6b62\u4e86\u8fd0\u884c\uff0c\u4e00\u5207\u6307\u9488\u90fd\u4f1a\u6d88\u4ea1\uff0c\u52a8\u6001\u5185\u5b58\u4f1a\u88ab\u64cd\u4f5c\u7cfb\u7edf\u56de\u6536\u3002\u65e2\u7136\u5982\u6b64\uff0c\u5728\u7a0b\u5e8f\u4e34\u7ec8\u524d\uff0c\u5c31\u53ef\u4ee5\u4e0d\u5fc5\u91ca\u653e\u5185\u5b58\u3001\u4e0d\u5fc5\u5c06\u6307\u9488\u8bbe\u7f6e\u4e3aNULL\u4e86\u3002\u7ec8\u4e8e\u53ef\u4ee5\u5077\u61d2\u800c\u4e0d\u4f1a\u53d1\u751f\u9519\u8bef\u4e86\u5427\uff1f<\/p>\n

\u60f3\u5f97\u7f8e\u3002\u5982\u679c\u522b\u4eba\u628a\u90a3\u6bb5\u7a0b\u5e8f\u53d6\u51fa\u6765\u7528\u5230\u5176\u5b83\u5730\u65b9\u600e\u4e48\u529e\uff1f<\/p>\n

\u00a0<\/p>\n

7.7 \u675c\u7edd\u201c\u91ce\u6307\u9488\u201d<\/font><\/strong><\/p>\n

\n\u201c\u91ce\u6307\u9488\u201d\u4e0d\u662fNULL\u6307\u9488\uff0c\u662f\u6307\u5411\u201c\u5783\u573e\u201d\u5185\u5b58\u7684\u6307\u9488\u3002\u4eba\u4eec\u4e00\u822c\u4e0d\u4f1a\u9519\u7528NULL\u6307\u9488\uff0c\u56e0\u4e3a\u7528if\u8bed\u53e5\u5f88\u5bb9\u6613\u5224\u65ad\u3002\u4f46\u662f\u201c\u91ce\u6307\u9488\u201d\u662f\u5f88\u5371\u9669\u7684\uff0cif\u8bed\u53e5\u5bf9\u5b83\u4e0d\u8d77\u4f5c\u7528\u3002<\/p>\n

\u201c\u91ce\u6307\u9488\u201d\u7684\u6210\u56e0\u4e3b\u8981\u6709\u4e24\u79cd\uff1a<\/p>\n

\n\uff081\uff09\u6307\u9488\u53d8\u91cf\u6ca1\u6709\u88ab\u521d\u59cb\u5316\u3002\u4efb\u4f55\u6307\u9488\u53d8\u91cf\u521a\u88ab\u521b\u5efa\u65f6\u4e0d\u4f1a\u81ea\u52a8\u6210\u4e3aNULL\u6307\u9488\uff0c\u5b83\u7684\u7f3a\u7701\u503c\u662f\u968f\u673a\u7684\uff0c\u5b83\u4f1a\u4e71\u6307\u4e00\u6c14\u3002\u6240\u4ee5\uff0c\u6307\u9488\u53d8\u91cf\u5728\u521b\u5efa\u7684\u540c\u65f6\u5e94\u5f53\u88ab\u521d\u59cb\u5316\uff0c\u8981\u4e48\u5c06\u6307\u9488\u8bbe\u7f6e\u4e3aNULL\uff0c\u8981\u4e48\u8ba9\u5b83\u6307\u5411\u5408\u6cd5\u7684\u5185\u5b58\u3002\u4f8b\u5982<\/p>\n

char *p = NULL;<\/p>\n

char *str = (char *) malloc(100);<\/p>\n

\uff082\uff09\u6307\u9488p\u88abfree\u6216\u8005delete\u4e4b\u540e\uff0c\u6ca1\u6709\u7f6e\u4e3aNULL\uff0c\u8ba9\u4eba\u8bef\u4ee5\u4e3ap\u662f\u4e2a\u5408\u6cd5\u7684\u6307\u9488\u3002\u53c2\u89c17.5\u8282\u3002<\/p>\n

\uff083\uff09\u6307\u9488\u64cd\u4f5c\u8d85\u8d8a\u4e86\u53d8\u91cf\u7684\u4f5c\u7528\u8303\u56f4\u3002\u8fd9\u79cd\u60c5\u51b5\u8ba9\u4eba\u9632\u4e0d\u80dc\u9632\uff0c\u793a\u4f8b\u7a0b\u5e8f\u5982\u4e0b\uff1a<\/p>\n

class A<\/p>\n

{<\/p>\n

public:<\/p>\n

void Func(void){ cout << \u201cFunc of
\nclass A\u201d << endl; }<\/p>\n

};<\/p>\n

void Test(void)<\/p>\n

{<\/p>\n

A *p;<\/p>\n

{<\/p>\n

A a;<\/p>\n

p = &a; \/\/ \u6ce8\u610f a \u7684\u751f\u547d\u671f<\/p>\n

}<\/p>\n

p->Func(); \/\/ p\u662f\u201c\u91ce\u6307\u9488\u201d<\/p>\n

}<\/p>\n

\n\u51fd\u6570Test\u5728\u6267\u884c\u8bed\u53e5p->Func()\u65f6\uff0c\u5bf9\u8c61a\u5df2\u7ecf\u6d88\u5931\uff0c\u800cp\u662f\u6307\u5411a\u7684\uff0c\u6240\u4ee5p\u5c31\u6210\u4e86\u201c\u91ce\u6307\u9488\u201d\u3002\u4f46\u5947\u602a\u7684\u662f\u6211\u8fd0\u884c\u8fd9\u4e2a\u7a0b\u5e8f\u65f6\u5c45\u7136\u6ca1\u6709\u51fa\u9519\uff0c\u8fd9\u53ef\u80fd\u4e0e\u7f16\u8bd1\u5668\u6709\u5173\u3002<\/p>\n

\u00a0<\/p>\n

7.8 \u6709\u4e86malloc\/free\u4e3a\u4ec0\u4e48\u8fd8\u8981new\/delete
\n\uff1f<\/font><\/strong><\/p>\n

\nmalloc\u4e0efree\u662fC++\/C\u8bed\u8a00\u7684\u6807\u51c6\u5e93\u51fd\u6570\uff0cnew\/delete\u662fC++\u7684\u8fd0\u7b97\u7b26\u3002\u5b83\u4eec\u90fd\u53ef\u7528\u4e8e\u7533\u8bf7\u52a8\u6001\u5185\u5b58\u548c\u91ca\u653e\u5185\u5b58\u3002<\/p>\n

\n\u5bf9\u4e8e\u975e\u5185\u90e8\u6570\u636e\u7c7b\u578b\u7684\u5bf9\u8c61\u800c\u8a00\uff0c\u5149\u7528maloc\/free\u65e0\u6cd5\u6ee1\u8db3\u52a8\u6001\u5bf9\u8c61\u7684\u8981\u6c42\u3002\u5bf9\u8c61\u5728\u521b\u5efa\u7684\u540c\u65f6\u8981\u81ea\u52a8\u6267\u884c\u6784\u9020\u51fd\u6570\uff0c\u5bf9\u8c61\u5728\u6d88\u4ea1\u4e4b\u524d\u8981\u81ea\u52a8\u6267\u884c\u6790\u6784\u51fd\u6570\u3002\u7531\u4e8emalloc\/free\u662f\u5e93\u51fd\u6570\u800c\u4e0d\u662f\u8fd0\u7b97\u7b26\uff0c\u4e0d\u5728\u7f16\u8bd1\u5668\u63a7\u5236\u6743\u9650\u4e4b\u5185\uff0c\u4e0d\u80fd\u591f\u628a\u6267\u884c\u6784\u9020\u51fd\u6570\u548c\u6790\u6784\u51fd\u6570\u7684\u4efb\u52a1\u5f3a\u52a0\u4e8emalloc\/free\u3002<\/p>\n

\n\u56e0\u6b64C++\u8bed\u8a00\u9700\u8981\u4e00\u4e2a\u80fd\u5b8c\u6210\u52a8\u6001\u5185\u5b58\u5206\u914d\u548c\u521d\u59cb\u5316\u5de5\u4f5c\u7684\u8fd0\u7b97\u7b26new\uff0c\u4ee5\u53ca\u4e00\u4e2a\u80fd\u5b8c\u6210\u6e05\u7406\u4e0e\u91ca\u653e\u5185\u5b58\u5de5\u4f5c\u7684\u8fd0\u7b97\u7b26delete\u3002\u6ce8\u610fnew\/delete\u4e0d\u662f\u5e93\u51fd\u6570\u3002<\/p>\n

\u6211\u4eec\u5148\u770b\u4e00\u770bmalloc\/free\u548cnew\/delete\u5982\u4f55\u5b9e\u73b0\u5bf9\u8c61\u7684\u52a8\u6001\u5185\u5b58\u7ba1\u7406\uff0c\u89c1\u793a\u4f8b7-8\u3002<\/p>\n\n\n\n\n\n
\n

class Obj<\/p>\n

{<\/p>\n

public :<\/p>\n

Obj(void){ cout <<
\n\u201cInitialization\u201d << endl; }<\/p>\n

~Obj(void){ cout << \u201cDestroy\u201d
\n<< endl; }<\/p>\n

void Initialize(void){ cout <<
\n\u201cInitialization\u201d << endl; }<\/p>\n

void Destroy(void){ cout <<
\n\u201cDestroy\u201d << endl; }<\/p>\n

};<\/p>\n<\/td>\n<\/tr>\n

\n

void UseMallocFree(void)<\/p>\n

{<\/p>\n

Obj *a = (obj *)malloc(sizeof(obj)); \/\/ \u7533\u8bf7\u52a8\u6001\u5185\u5b58<\/p>\n

a->Initialize(); \/\/ \u521d\u59cb\u5316<\/p>\n

\/\/\u2026<\/p>\n

a->Destroy(); \/\/ \u6e05\u9664\u5de5\u4f5c<\/p>\n

free(a); \/\/ \u91ca\u653e\u5185\u5b58<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n

\n

void UseNewDelete(void)<\/p>\n

{<\/p>\n

Obj *a = new Obj; \/\/ \u7533\u8bf7\u52a8\u6001\u5185\u5b58\u5e76\u4e14\u521d\u59cb\u5316<\/p>\n

\/\/\u2026<\/p>\n

delete a; \/\/ \u6e05\u9664\u5e76\u4e14\u91ca\u653e\u5185\u5b58<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-8 \u7528malloc\/free\u548cnew\/delete\u5982\u4f55\u5b9e\u73b0\u5bf9\u8c61\u7684\u52a8\u6001\u5185\u5b58\u7ba1\u7406<\/p>\n

\n\u7c7bObj\u7684\u51fd\u6570Initialize\u6a21\u62df\u4e86\u6784\u9020\u51fd\u6570\u7684\u529f\u80fd\uff0c\u51fd\u6570Destroy\u6a21\u62df\u4e86\u6790\u6784\u51fd\u6570\u7684\u529f\u80fd\u3002\u51fd\u6570UseMallocFree\u4e2d\uff0c\u7531\u4e8emalloc\/free\u4e0d\u80fd\u6267\u884c\u6784\u9020\u51fd\u6570\u4e0e\u6790\u6784\u51fd\u6570\uff0c\u5fc5\u987b\u8c03\u7528\u6210\u5458\u51fd\u6570Initialize\u548cDestroy\u6765\u5b8c\u6210\u521d\u59cb\u5316\u4e0e\u6e05\u9664\u5de5\u4f5c\u3002\u51fd\u6570UseNewDelete\u5219\u7b80\u5355\u5f97\u591a\u3002<\/p>\n

\n\u6240\u4ee5\u6211\u4eec\u4e0d\u8981\u4f01\u56fe\u7528malloc\/free\u6765\u5b8c\u6210\u52a8\u6001\u5bf9\u8c61\u7684\u5185\u5b58\u7ba1\u7406\uff0c\u5e94\u8be5\u7528new\/delete\u3002\u7531\u4e8e\u5185\u90e8\u6570\u636e\u7c7b\u578b\u7684\u201c\u5bf9\u8c61\u201d\u6ca1\u6709\u6784\u9020\u4e0e\u6790\u6784\u7684\u8fc7\u7a0b\uff0c\u5bf9\u5b83\u4eec\u800c\u8a00malloc\/free\u548cnew\/delete\u662f\u7b49\u4ef7\u7684\u3002<\/p>\n

\n\u65e2\u7136new\/delete\u7684\u529f\u80fd\u5b8c\u5168\u8986\u76d6\u4e86malloc\/free\uff0c\u4e3a\u4ec0\u4e48C++\u4e0d\u628amalloc\/free\u6dd8\u6c70\u51fa\u5c40\u5462\uff1f\u8fd9\u662f\u56e0\u4e3aC++\u7a0b\u5e8f\u7ecf\u5e38\u8981\u8c03\u7528C\u51fd\u6570\uff0c\u800cC\u7a0b\u5e8f\u53ea\u80fd\u7528malloc\/free\u7ba1\u7406\u52a8\u6001\u5185\u5b58\u3002<\/p>\n

\n\u5982\u679c\u7528free\u91ca\u653e\u201cnew\u521b\u5efa\u7684\u52a8\u6001\u5bf9\u8c61\u201d\uff0c\u90a3\u4e48\u8be5\u5bf9\u8c61\u56e0\u65e0\u6cd5\u6267\u884c\u6790\u6784\u51fd\u6570\u800c\u53ef\u80fd\u5bfc\u81f4\u7a0b\u5e8f\u51fa\u9519\u3002\u5982\u679c\u7528delete\u91ca\u653e\u201cmalloc\u7533\u8bf7\u7684\u52a8\u6001\u5185\u5b58\u201d\uff0c\u7406\u8bba\u4e0a\u8bb2\u7a0b\u5e8f\u4e0d\u4f1a\u51fa\u9519\uff0c\u4f46\u662f\u8be5\u7a0b\u5e8f\u7684\u53ef\u8bfb\u6027\u5f88\u5dee\u3002\u6240\u4ee5new\/delete\u5fc5\u987b\u914d\u5bf9\u4f7f\u7528\uff0cmalloc\/free\u4e5f\u4e00\u6837\u3002<\/p>\n

\u00a0<\/p>\n

7.9 \u5185\u5b58\u8017\u5c3d\u600e\u4e48\u529e\uff1f<\/font><\/strong><\/p>\n

\n\u5982\u679c\u5728\u7533\u8bf7\u52a8\u6001\u5185\u5b58\u65f6\u627e\u4e0d\u5230\u8db3\u591f\u5927\u7684\u5185\u5b58\u5757\uff0cmalloc\u548cnew\u5c06\u8fd4\u56deNULL\u6307\u9488\uff0c\u5ba3\u544a\u5185\u5b58\u7533\u8bf7\u5931\u8d25\u3002\u901a\u5e38\u6709\u4e09\u79cd\u65b9\u5f0f\u5904\u7406\u201c\u5185\u5b58\u8017\u5c3d\u201d\u95ee\u9898\u3002<\/p>\n

\uff081\uff09\u5224\u65ad\u6307\u9488\u662f\u5426\u4e3aNULL\uff0c\u5982\u679c\u662f\u5219\u9a6c\u4e0a\u7528return\u8bed\u53e5\u7ec8\u6b62\u672c\u51fd\u6570\u3002\u4f8b\u5982\uff1a<\/p>\n

void Func(void)<\/p>\n

{<\/p>\n

A *a = new A;<\/p>\n

if(a == NULL)<\/p>\n

{<\/p>\n

return;<\/p>\n

}<\/p>\n

\u2026<\/p>\n

}<\/p>\n

\uff082\uff09\u5224\u65ad\u6307\u9488\u662f\u5426\u4e3aNULL\uff0c\u5982\u679c\u662f\u5219\u9a6c\u4e0a\u7528exit(1)\u7ec8\u6b62\u6574\u4e2a\u7a0b\u5e8f\u7684\u8fd0\u884c\u3002\u4f8b\u5982\uff1a<\/p>\n

void Func(void)<\/p>\n

{<\/p>\n

A *a = new A;<\/p>\n

if(a == NULL)<\/p>\n

{<\/p>\n

cout << \u201cMemory Exhausted\u201d
\n<< endl;<\/p>\n

exit(1);<\/p>\n

}<\/p>\n

\u2026<\/p>\n

}<\/p>\n

\uff083\uff09\u4e3anew\u548cmalloc\u8bbe\u7f6e\u5f02\u5e38\u5904\u7406\u51fd\u6570\u3002\u4f8b\u5982Visual
\nC++\u53ef\u4ee5\u7528_set_new_hander\u51fd\u6570\u4e3anew\u8bbe\u7f6e\u7528\u6237\u81ea\u5df1\u5b9a\u4e49\u7684\u5f02\u5e38\u5904\u7406\u51fd\u6570\uff0c\u4e5f\u53ef\u4ee5\u8ba9malloc\u4eab\u7528\u4e0enew\u76f8\u540c\u7684\u5f02\u5e38\u5904\u7406\u51fd\u6570\u3002\u8be6\u7ec6\u5185\u5bb9\u8bf7\u53c2\u8003C++\u4f7f\u7528\u624b\u518c\u3002<\/p>\n

\u00a0<\/p>\n

\n\u4e0a\u8ff0\uff081\uff09\uff082\uff09\u65b9\u5f0f\u4f7f\u7528\u6700\u666e\u904d\u3002\u5982\u679c\u4e00\u4e2a\u51fd\u6570\u5185\u6709\u591a\u5904\u9700\u8981\u7533\u8bf7\u52a8\u6001\u5185\u5b58\uff0c\u90a3\u4e48\u65b9\u5f0f\uff081\uff09\u5c31\u663e\u5f97\u529b\u4e0d\u4ece\u5fc3\uff08\u91ca\u653e\u5185\u5b58\u5f88\u9ebb\u70e6\uff09\uff0c\u5e94\u8be5\u7528\u65b9\u5f0f\uff082\uff09\u6765\u5904\u7406\u3002<\/p>\n

\u5f88\u591a\u4eba\u4e0d\u5fcd\u5fc3\u7528exit(1)\uff0c\u95ee\uff1a\u201c\u4e0d\u7f16\u5199\u51fa\u9519\u5904\u7406\u7a0b\u5e8f\uff0c\u8ba9\u64cd\u4f5c\u7cfb\u7edf\u81ea\u5df1\u89e3\u51b3\u884c\u4e0d\u884c\uff1f\u201d<\/p>\n

\u4e0d\u884c\u3002\u5982\u679c\u53d1\u751f\u201c\u5185\u5b58\u8017\u5c3d\u201d\u8fd9\u6837\u7684\u4e8b\u60c5\uff0c\u4e00\u822c\u8bf4\u6765\u5e94\u7528\u7a0b\u5e8f\u5df2\u7ecf\u65e0\u836f\u53ef\u6551\u3002\u5982\u679c\u4e0d\u7528exit(1)
\n\u628a\u574f\u7a0b\u5e8f\u6740\u6b7b\uff0c\u5b83\u53ef\u80fd\u4f1a\u5bb3\u6b7b\u64cd\u4f5c\u7cfb\u7edf\u3002\u9053\u7406\u5982\u540c\uff1a\u5982\u679c\u4e0d\u628a\u6b79\u5f92\u51fb\u6bd9\uff0c\u6b79\u5f92\u5728\u8001\u6b7b\u4e4b\u524d\u4f1a\u72af\u4e0b\u66f4\u591a\u7684\u7f6a\u3002<\/p>\n

\n\u6709\u4e00\u4e2a\u5f88\u91cd\u8981\u7684\u73b0\u8c61\u8981\u544a\u8bc9\u5927\u5bb6\u3002\u5bf9\u4e8e32\u4f4d\u4ee5\u4e0a\u7684\u5e94\u7528\u7a0b\u5e8f\u800c\u8a00\uff0c\u65e0\u8bba\u600e\u6837\u4f7f\u7528malloc\u4e0enew\uff0c\u51e0\u4e4e\u4e0d\u53ef\u80fd\u5bfc\u81f4\u201c\u5185\u5b58\u8017\u5c3d\u201d\u3002\u6211\u5728Windows
\n98\u4e0b\u7528Visual
\nC++\u7f16\u5199\u4e86\u6d4b\u8bd5\u7a0b\u5e8f\uff0c\u89c1\u793a\u4f8b7-9\u3002\u8fd9\u4e2a\u7a0b\u5e8f\u4f1a\u65e0\u4f11\u6b62\u5730\u8fd0\u884c\u4e0b\u53bb\uff0c\u6839\u672c\u4e0d\u4f1a\u7ec8\u6b62\u3002\u56e0\u4e3a32\u4f4d\u64cd\u4f5c\u7cfb\u7edf\u652f\u6301\u201c\u865a\u5b58\u201d\uff0c\u5185\u5b58\u7528\u5b8c\u4e86\uff0c\u81ea\u52a8\u7528\u786c\u76d8\u7a7a\u95f4\u9876\u66ff\u3002\u6211\u53ea\u542c\u5230\u786c\u76d8\u560e\u5431\u560e\u5431\u5730\u54cd\uff0cWindow
\n98\u5df2\u7ecf\u7d2f\u5f97\u5bf9\u952e\u76d8\u3001\u9f20\u6807\u6beb\u65e0\u53cd\u5e94\u3002<\/p>\n

\n\u6211\u53ef\u4ee5\u5f97\u51fa\u8fd9\u4e48\u4e00\u4e2a\u7ed3\u8bba\uff1a\u5bf9\u4e8e32\u4f4d\u4ee5\u4e0a\u7684\u5e94\u7528\u7a0b\u5e8f\uff0c\u201c\u5185\u5b58\u8017\u5c3d\u201d\u9519\u8bef\u5904\u7406\u7a0b\u5e8f\u6beb\u65e0\u7528\u5904\u3002\u8fd9\u4e0b\u53ef\u628aUnix\u548cWindows\u7a0b\u5e8f\u5458\u4eec\u4e50\u574f\u4e86\uff1a\u53cd\u6b63\u9519\u8bef\u5904\u7406\u7a0b\u5e8f\u4e0d\u8d77\u4f5c\u7528\uff0c\u6211\u5c31\u4e0d\u5199\u4e86\uff0c\u7701\u4e86\u5f88\u591a\u9ebb\u70e6\u3002<\/p>\n

\u6211\u4e0d\u60f3\u8bef\u5bfc\u8bfb\u8005\uff0c\u5fc5\u987b\u5f3a\u8c03\uff1a\u4e0d\u52a0\u9519\u8bef\u5904\u7406\u5c06\u5bfc\u81f4\u7a0b\u5e8f\u7684\u8d28\u91cf\u5f88\u5dee\uff0c\u5343\u4e07\u4e0d\u53ef\u56e0\u5c0f\u5931\u5927\u3002<\/p>\n\n\n\n
\n

void main(void)<\/p>\n

{<\/p>\n

float *p = NULL;<\/p>\n

while(TRUE)<\/p>\n

{<\/p>\n

p = new float[1000000];<\/p>\n

cout << \u201ceat memory\u201d
\n<< endl;<\/p>\n

if(p==NULL)<\/p>\n

exit(1);<\/p>\n

}<\/p>\n

}<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u793a\u4f8b7-9\u8bd5\u56fe\u8017\u5c3d\u64cd\u4f5c\u7cfb\u7edf\u7684\u5185\u5b58<\/p>\n

\u00a0<\/p>\n

7.10 malloc\/free
\n\u7684\u4f7f\u7528\u8981\u70b9<\/font><\/strong><\/p>\n

\u51fd\u6570malloc\u7684\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n

void * malloc(size_t size);<\/p>\n

\u7528malloc\u7533\u8bf7\u4e00\u5757\u957f\u5ea6\u4e3alength\u7684\u6574\u6570\u7c7b\u578b\u7684\u5185\u5b58\uff0c\u7a0b\u5e8f\u5982\u4e0b\uff1a<\/p>\n

int *p = (int *) malloc(sizeof(int) * length);<\/p>\n

\u6211\u4eec\u5e94\u5f53\u628a\u6ce8\u610f\u529b\u96c6\u4e2d\u5728\u4e24\u4e2a\u8981\u7d20\u4e0a\uff1a\u201c\u7c7b\u578b\u8f6c\u6362\u201d\u548c\u201csizeof\u201d\u3002<\/p>\n

\u25c6malloc\u8fd4\u56de\u503c\u7684\u7c7b\u578b\u662fvoid *\uff0c\u6240\u4ee5\u5728\u8c03\u7528malloc\u65f6\u8981\u663e\u5f0f\u5730\u8fdb\u884c\u7c7b\u578b\u8f6c\u6362\uff0c\u5c06void *
\n\u8f6c\u6362\u6210\u6240\u9700\u8981\u7684\u6307\u9488\u7c7b\u578b\u3002<\/p>\n

\u25c6malloc\u51fd\u6570\u672c\u8eab\u5e76\u4e0d\u8bc6\u522b\u8981\u7533\u8bf7\u7684\u5185\u5b58\u662f\u4ec0\u4e48\u7c7b\u578b\uff0c\u5b83\u53ea\u5173\u5fc3\u5185\u5b58\u7684\u603b\u5b57\u8282\u6570\u3002\u6211\u4eec\u901a\u5e38\u8bb0\u4e0d\u4f4fint,
\nfloat\u7b49\u6570\u636e\u7c7b\u578b\u7684\u53d8\u91cf\u7684\u786e\u5207\u5b57\u8282\u6570\u3002\u4f8b\u5982int\u53d8\u91cf\u572816\u4f4d\u7cfb\u7edf\u4e0b\u662f2\u4e2a\u5b57\u8282\uff0c\u572832\u4f4d\u4e0b\u662f4\u4e2a\u5b57\u8282\uff1b\u800cfloat\u53d8\u91cf\u572816\u4f4d\u7cfb\u7edf\u4e0b\u662f4\u4e2a\u5b57\u8282\uff0c\u572832\u4f4d\u4e0b\u4e5f\u662f4\u4e2a\u5b57\u8282\u3002\u6700\u597d\u7528\u4ee5\u4e0b\u7a0b\u5e8f\u4f5c\u4e00\u6b21\u6d4b\u8bd5\uff1a<\/p>\n

cout << sizeof(char)
\n<< endl;<\/p>\n

cout << sizeof(int)
\n<< endl;<\/p>\n

cout << sizeof(unsigned int)
\n<< endl;<\/p>\n

cout << sizeof(long)
\n<< endl;<\/p>\n

cout << sizeof(unsigned long)
\n<< endl;<\/p>\n

cout << sizeof(float)
\n<< endl;<\/p>\n

cout << sizeof(double)
\n<< endl;<\/p>\n

cout << sizeof(void *)
\n<< endl;<\/p>\n

\u5728malloc\u7684\u201c()\u201d\u4e2d\u4f7f\u7528sizeof\u8fd0\u7b97\u7b26\u662f\u826f\u597d\u7684\u98ce\u683c\uff0c\u4f46\u8981\u5f53\u5fc3\u6709\u65f6\u6211\u4eec\u4f1a\u660f\u4e86\u5934\uff0c\u5199\u51fa p =
\nmalloc(sizeof(p))\u8fd9\u6837\u7684\u7a0b\u5e8f\u6765\u3002<\/p>\n

\u25c6\u51fd\u6570free\u7684\u539f\u578b\u5982\u4e0b\uff1a<\/p>\n

void free( void * memblock );<\/p>\n

\n\u4e3a\u4ec0\u4e48free\u51fd\u6570\u4e0d\u8c61malloc\u51fd\u6570\u90a3\u6837\u590d\u6742\u5462\uff1f\u8fd9\u662f\u56e0\u4e3a\u6307\u9488p\u7684\u7c7b\u578b\u4ee5\u53ca\u5b83\u6240\u6307\u7684\u5185\u5b58\u7684\u5bb9\u91cf\u4e8b\u5148\u90fd\u662f\u77e5\u9053\u7684\uff0c\u8bed\u53e5free(p)\u80fd\u6b63\u786e\u5730\u91ca\u653e\u5185\u5b58\u3002\u5982\u679cp\u662fNULL\u6307\u9488\uff0c\u90a3\u4e48free\u5bf9p\u65e0\u8bba\u64cd\u4f5c\u591a\u5c11\u6b21\u90fd\u4e0d\u4f1a\u51fa\u95ee\u9898\u3002\u5982\u679cp\u4e0d\u662fNULL\u6307\u9488\uff0c\u90a3\u4e48free\u5bf9p\u8fde\u7eed\u64cd\u4f5c\u4e24\u6b21\u5c31\u4f1a\u5bfc\u81f4\u7a0b\u5e8f\u8fd0\u884c\u9519\u8bef\u3002<\/p>\n

\u00a0<\/p>\n

7.11 new\/delete \u7684\u4f7f\u7528\u8981\u70b9<\/font><\/strong><\/p>\n

\u8fd0\u7b97\u7b26new\u4f7f\u7528\u8d77\u6765\u8981\u6bd4\u51fd\u6570malloc\u7b80\u5355\u5f97\u591a\uff0c\u4f8b\u5982\uff1a<\/p>\n

int *p1 = (int *)malloc(sizeof(int) * length);<\/p>\n

int *p2 = new int[length];<\/p>\n

\n\u8fd9\u662f\u56e0\u4e3anew\u5185\u7f6e\u4e86sizeof\u3001\u7c7b\u578b\u8f6c\u6362\u548c\u7c7b\u578b\u5b89\u5168\u68c0\u67e5\u529f\u80fd\u3002\u5bf9\u4e8e\u975e\u5185\u90e8\u6570\u636e\u7c7b\u578b\u7684\u5bf9\u8c61\u800c\u8a00\uff0cnew\u5728\u521b\u5efa\u52a8\u6001\u5bf9\u8c61\u7684\u540c\u65f6\u5b8c\u6210\u4e86\u521d\u59cb\u5316\u5de5\u4f5c\u3002\u5982\u679c\u5bf9\u8c61\u6709\u591a\u4e2a\u6784\u9020\u51fd\u6570\uff0c\u90a3\u4e48new\u7684\u8bed\u53e5\u4e5f\u53ef\u4ee5\u6709\u591a\u79cd\u5f62\u5f0f\u3002\u4f8b\u5982<\/p>\n

class Obj<\/p>\n

{<\/p>\n

public :<\/p>\n

Obj(void); \/\/ \u65e0\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570<\/p>\n

Obj(int x); \/\/ \u5e26\u4e00\u4e2a\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570<\/p>\n

\u2026<\/p>\n

}<\/p>\n

void Test(void)<\/p>\n

{<\/p>\n

Obj *a = new Obj;<\/p>\n

Obj *b = new Obj(1); \/\/ \u521d\u503c\u4e3a1<\/p>\n

\u2026<\/p>\n

delete a;<\/p>\n

delete b;<\/p>\n

}<\/p>\n

\u5982\u679c\u7528new\u521b\u5efa\u5bf9\u8c61\u6570\u7ec4\uff0c\u90a3\u4e48\u53ea\u80fd\u4f7f\u7528\u5bf9\u8c61\u7684\u65e0\u53c2\u6570\u6784\u9020\u51fd\u6570\u3002\u4f8b\u5982<\/p>\n

Obj *objects = new Obj[100]; \/\/ \u521b\u5efa100\u4e2a\u52a8\u6001\u5bf9\u8c61<\/p>\n

\u4e0d\u80fd\u5199\u6210<\/p>\n

Obj *objects = new Obj[100](1);\/\/ \u521b\u5efa100\u4e2a\u52a8\u6001\u5bf9\u8c61\u7684\u540c\u65f6\u8d4b\u521d\u503c1<\/p>\n

\u5728\u7528delete\u91ca\u653e\u5bf9\u8c61\u6570\u7ec4\u65f6\uff0c\u7559\u610f\u4e0d\u8981\u4e22\u4e86\u7b26\u53f7\u2018[]\u2019\u3002\u4f8b\u5982<\/p>\n

delete []objects; \/\/ \u6b63\u786e\u7684\u7528\u6cd5<\/p>\n

delete objects; \/\/ \u9519\u8bef\u7684\u7528\u6cd5<\/p>\n

\u540e\u8005\u76f8\u5f53\u4e8edelete objects[0]\uff0c\u6f0f\u6389\u4e86\u53e6\u591699\u4e2a\u5bf9\u8c61\u3002<\/p>\n

\u00a0<\/p>\n

7.12 \u4e00\u4e9b\u5fc3\u5f97\u4f53\u4f1a<\/font><\/strong><\/p>\n

\n\u6211\u8ba4\u8bc6\u4e0d\u5c11\u6280\u672f\u4e0d\u9519\u7684C++\/C\u7a0b\u5e8f\u5458\uff0c\u5f88\u5c11\u6709\u4eba\u80fd\u62cd\u62cd\u80f8\u812f\u8bf4\u901a\u6653\u6307\u9488\u4e0e\u5185\u5b58\u7ba1\u7406\uff08\u5305\u62ec\u6211\u81ea\u5df1\uff09\u3002\u6211\u6700\u521d\u5b66\u4e60C\u8bed\u8a00\u65f6\u7279\u522b\u6015\u6307\u9488\uff0c\u5bfc\u81f4\u6211\u5f00\u53d1\u7b2c\u4e00\u4e2a\u5e94\u7528\u8f6f\u4ef6\uff08\u7ea61\u4e07\u884cC\u4ee3\u7801\uff09\u65f6\u6ca1\u6709\u4f7f\u7528\u4e00\u4e2a\u6307\u9488\uff0c\u5168\u7528\u6570\u7ec4\u6765\u9876\u66ff\u6307\u9488\uff0c\u5b9e\u5728\u8822\u7b28\u5f97\u8fc7\u5206\u3002\u8eb2\u907f\u6307\u9488\u4e0d\u662f\u529e\u6cd5\uff0c\u540e\u6765\u6211\u6539\u5199\u4e86\u8fd9\u4e2a\u8f6f\u4ef6\uff0c\u4ee3\u7801\u91cf\u7f29\u5c0f\u5230\u539f\u5148\u7684\u4e00\u534a\u3002<\/p>\n

\u6211\u7684\u7ecf\u9a8c\u6559\u8bad\u662f\uff1a<\/p>\n

\uff081\uff09\u8d8a\u662f\u6015\u6307\u9488\uff0c\u5c31\u8d8a\u8981\u4f7f\u7528\u6307\u9488\u3002\u4e0d\u4f1a\u6b63\u786e\u4f7f\u7528\u6307\u9488\uff0c\u80af\u5b9a\u7b97\u4e0d\u4e0a\u662f\u5408\u683c\u7684\u7a0b\u5e8f\u5458\u3002<\/p>\n

\uff082\uff09\u5fc5\u987b\u517b\u6210\u201c\u4f7f\u7528\u8c03\u8bd5\u5668\u9010\u6b65\u8ddf\u8e2a\u7a0b\u5e8f\u201d\u7684\u4e60\u60ef\uff0c\u53ea\u6709\u8fd9\u6837\u624d\u80fd\u53d1\u73b0\u95ee\u9898\u7684\u672c\u8d28\u3002<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

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