{"id":80,"date":"2022-02-26T21:44:55","date_gmt":"2022-02-26T13:44:55","guid":{"rendered":"https:\/\/blog.lickoo.fun\/?p=80"},"modified":"2022-02-26T21:44:57","modified_gmt":"2022-02-26T13:44:57","slug":"c%e8%af%ad%e8%a8%80%e6%8c%87%e9%92%88%e5%bc%ba%e5%88%b6%e7%b1%bb%e5%9e%8b%e8%bd%ac%e6%8d%a2","status":"publish","type":"post","link":"https:\/\/blog.lickoo.fun\/?p=80","title":{"rendered":"C\u8bed\u8a00\u6307\u9488\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362"},"content":{"rendered":"\n\n\n\n\n<\/head>\n\n

\u6982\u8981\uff1a<\/p>\n

C\u8bed\u8a00\u4e2d\uff0c\u4efb\u4f55\u4e00\u4e2a\u53d8\u91cf\u90fd\u5fc5\u987b\u5360\u6709\u4e00\u4e2a\u5730\u5740\uff0c\u800c\u8fd9\u4e2a\u5730\u5740\u7a7a\u95f4\u5185\u76840-1\u4ee3\u7801\u5c31\u662f\u8fd9\u4e2a\u53d8\u91cf\u7684\u503c\u3002\u4e0d\u540c\u7684\u6570\u636e\u7c7b\u578b\u5360\u6709\u7684\u7a7a\u95f4\u5927\u5c0f\u4e0d\u4e00\uff0c\u4f46\u662f\u4ed6\u4eec\u90fd\u5fc5\u987b\u6709\u4e2a\u5730\u5740\uff0c\u800c\u8fd9\u4e2a\u5730\u5740\u5c31\u662f\u786c\u4ef6\u8bbf\u95ee\u7684\u4f9d\u636e\uff0c\u800c\u540d\u5b57\u53ea\u662f\u63d0\u4f9b\u7ed9\u7a0b\u5e8f\u5458\u7684\u4e00\u79cd\u8bb0\u4f4f\u8fd9\u4e2a\u5730\u5740\u7684\u65b9\u4fbf\u4e00\u70b9\u7684\u65b9\u6cd5\u3002\u4f46\u662f\uff0c\u4e0d\u540c\u7684\u53d8\u91cf\u5728\u673a\u5668\u4e2d\u90fd\u662f0-1\u4ee3\u7801\uff0c\u6240\u4ee5\uff0c\u6211\u4eec\u4e0d\u80fd\u7b80\u5355\u7684\u901a\u8fc7\u68c0\u67e5\u4e00\u4e2a\u503c\u7684\u4f4d\u6765\u5224\u65ad\u5b83\u7684\u7c7b\u578b\u3002<\/p>\n

\u4f8b\u5982\uff0c\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n

int a;\n\n float b;\n\ndouble c;\n\n long double d;\n<\/code><\/pre>\n
(\u5047\u8bbe\u5b83\u4eec\u6240\u5360\u7684\u5b57\u8282\u5206\u522b\u662f4\u30018\u30018\u300110\uff0c\u800c\u4e14\u8fde\u7eed\u5b58\u50a8\u4e8e\u67d0\u4e2a\u5730\u5740\u7a7a\u95f4\uff0c\u8d77\u59cb\u5730\u5740\u662f100\uff0c\u5219\u6211\u4eec\u53ef\u4ee5\u5f97\u5230\u5982\u4e0b\u5185\u5b58\u5206\u5e03)<\/p>\n
a\u53d8\u91cf\u5c31\u662f\u7531\u4ee5\u5730\u5740100\u5f00\u59cb\u5230103\u7ed3\u675f\u76844\u4e2a\u5b57\u8282\u5185\u5b58\u7a7a\u95f4\u5185\u76840-1\u4ee3\u7801\u7ec4\u6210\u3002b\u53d8\u91cf\u5219\u662f\u7531\u4ee5\u5730\u5740104\u5f00\u59cb\u5230112\u7ed3\u675f\u76848\u4e2a\u5b57\u8282\u5185\u5b58\u7a7a\u95f4\u5185\u76840-1\u4ee3\u7801\u7ec4\u6210\u3002\u800c\u5728\u673a\u5668\u4e2d\uff0c\u8fd9\u4e9b\u5185\u5b58\u90fd\u662f\u8fde\u7eed\u76840-1\u4ee3\u7801\uff0c\u673a\u5668\u5e76\u4e0d\u77e5\u9053100~103\u662f\u6574\u578b\u800c104~111\u662ffloat\u578b\uff0c\u6240\u6709\u8fd9\u4e9b\u7c7b\u578b\u90fd\u662f\u7f16\u8bd1\u5668\u544a\u77e5\u7684\u3002\u5f53\u6211\u4eec\u7528a\u65f6\uff0c\u7531\u4e8e\u524d\u9762\u628aa\u5b9a\u4e49\u4e3aint\u578b\uff0c\u5219\u7f16\u8bd1\u5668\u77e5\u9053\u4ecea\u7684\u5730\u5740\u5f00\u59cb\u5411\u540e\u53d64\u4e2a\u5b57\u8282\u518d\u628a\u5b83\u89e3\u91ca\u6210int\u578b\u3002\u90a3\u4e48(float)a\uff0c\u5c31\u662f\u5148\u6309\u7167int\u7c7b\u578b\u53d6\u51fa\u8be5\u6570\u503c\uff0c\u518d\u5c06\u8be5\u6570\u503c\u6309\u7167int to float\u7684\u89c4\u5219\u8f6c\u6362\u6210float\u578b\u3002\u6240\u4ee5\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u5c31\u662f\u6309\u7167\u67d0\u4e2a\u53d8\u91cf\u7684\u7c7b\u578b\u53d6\u51fa\u8be5\u53d8\u91cf\u7684\u503c\uff0c\u518d\u6309\u7167***to***\u7684\u89c4\u5219\u8fdb\u884c\u5f3a\u5236\u8f6c\u8f6c\u6362\u3002\u5982\u679c\u662f(\u7c7b\u578b\u540d)\u5e38\u6570\uff0c\u5219\u662f\u5c06\u8be5\u5e38\u6570\u6309\u7167\u5e38\u6570to\u7c7b\u578b \u7684\u89c4\u5219\u8fdb\u884c\u5f3a\u5236\u8f6c\u6362\u3002\n\u6307\u9488\u4e5f\u662f\u4e00\u4e2a\u53d8\u91cf\uff0c\u5b83\u81ea\u5df1\u5360\u636e\u4e00\u4e2a4\u4e2a\u5b57\u8282\u7684\u5730\u5740\u7a7a\u95f4\uff08\u7531\u4e8e\u7a0b\u5e8f\u7684\u5bfb\u5740\u7a7a\u95f4\u662f2^32\u6b21\u65b9\uff0c\u53734GB\uff0c\u6240\u4ee5\u75284\u4e2a\u5b57\u8282\u8868\u793a\u6307\u9488\u5c31\u5df2\u7ecf\u80fd\u6307\u5411\u4efb\u4f55\u7a0b\u5e8f\u80fd\u591f\u5bfb\u5740\u5230\u7684\u7a7a\u95f4\u4e86\uff0c\u6240\u4ee5\u6307\u9488\u7684\u5927\u5c0f\u4e3a4\u5b57\u8282\uff09\uff0c\u4ed6\u7684\u503c\u662f\u53e6\u4e00\u4e2a\u4e1c\u897f\u7684\u5730\u5740\uff0c\u8fd9\u4e2a\u4e1c\u897f\u53ef\u4ee5\u662f\u666e\u901a\u53d8\u91cf\uff0c\u7ed3\u6784\u4f53\uff0c\u8fd8\u53ef\u4ee5\u662f\u4e2a\u51fd\u6570\u7b49\u7b49\u3002\u7531\u4e8e\uff0c\u6307\u9488\u7684\u5927\u5c0f\u662f4\u5b57\u8282\uff0c\u6240\u4ee5\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u6307\u9488\u5f3a\u5236\u8f6c\u6362\u6210int\u578b\u6216\u8005\u5176\u4ed6\u7c7b\u578b\u3002\u540c\u6837\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u5c06\u4efb\u4f55\u4e00\u4e2a\u5e38\u6570\u8f6c\u6362\u6210int\u578b\u518d\u8d4b\u503c\u7ed9\u6307\u9488\u3002\u6240\u6709\u7684\u6307\u9488\u6240\u5360\u7684\u7a7a\u95f4\u5927\u5c0f\u90fd\u662f4\u5b57\u8282\uff0c\u4ed6\u4eec\u53ea\u662f\u58f0\u660e\u7684\u7c7b\u578b\u4e0d\u540c\uff0c\u4ed6\u4eec\u7684\u503c\u90fd\u662f\u5730\u5740\u6307\u5411\u67d0\u4e2a\u4e1c\u897f\uff0c\u4ed6\u4eec\u5bf9\u4e8e\u673a\u5668\u6765\u8bf4\u6ca1\u6709\u672c\u8d28\u5dee\u522b\uff0c\u4ed6\u4eec\u4e4b\u95f4\u53ef\u4ee5\u8fdb\u884c\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u3002\n\u6307\u9488 to \u6307\u9488\u7684\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u662f\u6307\u5c06\u6307\u9488\u6240\u6307\u7684\u5185\u5bb9\u7684\u7c7b\u578b\u7531\u539f\u5148\u7684\u7c7b\u578b\u8f6c\u6362\u4e3a\u540e\u9762\u7684\u7c7b\u578b\u3002<\/p>\n
int a = 1;\n\nint *p = &a;\n\nfloat *p1 = (float\\*)p;\n<\/code><\/pre>\n
\u5219p\u548cp1\u7684\u503c\u90fd\u662f&a\uff0c\u4f46\u662f*p\u662f\u5c06&a\u5730\u5740\u4e2d\u7684\u503c\u6309\u7167int\u578b\u53d8\u91cf\u8fdb\u884c\u89e3\u91ca\uff0c\u800c*p1\u5219\u662f\u5c06&a\u5730\u5740\u4e2d\u7684\u503c\u6309\u7167float\u578b\u53d8\u91cf\u8fdb\u884c\u89e3\u91ca\u3002<\/p>\n
 <\/p>\n
\u9274\u4e8e\u6307\u9488\u4e4b\u95f4\u8fd9\u79cd\u7075\u6d3b\u7684\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u7684\u9700\u6c42\u548c\u51fa\u4e8e\u7b80\u5316\u4ee3\u7801\u7684\u8003\u8651\uff0cANSI C\u5f15\u5165\u4e86\u7a7a\u6307\u9488\u5373void*\u3002void\u6307\u9488\u53c8\u540d\u4e07\u80fd\u6307\u9488\uff0c\u5728\u73b0\u5728\u7684\u5f88\u591a\u7a0b\u5e8f\u4e2d\uff0c\u5f53\u53c2\u6570\u4e0d\u786e\u5b9a\u65f6\u5c31\u7528\u4e07\u80fd\u6307\u9488\u4ee3\u66ff\uff0c\u8fd9\u4e00\u7c7b\u7684\u6307\u9488\u5728\u7ebf\u7a0b\\\u8fdb\u7a0b\u51fd\u6570\u91cc\u7279\u522b\u5e38\u89c1\u3002<\/p>\n
ANSI C\u89c4\u5b9a\uff0cvoid\u6307\u9488\u53ef\u4ee5\u590d\u5236\u7ed9\u5176\u4ed6\u4efb\u610f\u7c7b\u578b\u7684\u6307\u9488\uff0c\u5176\u4ed6\u4efb\u610f\u7c7b\u578b\u7684\u6307\u9488\u4e5f\u53ef\u4ee5\u590d\u5236\u7ed9void\u6307\u9488\uff0c\u4ed6\u4eec\u4e4b\u95f4\u590d\u5236\u4e0d\u9700\u8981\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u3002\u5f53\u7136\u4efb\u4f55\u5730\u5740\u4e5f\u53ef\u4ee5\u590d\u5236\u7ed9void\u578b\u6307\u9488\u3002\u6211\u4eec\u5728\u300a\u7f51\u7edc\u7f16\u7a0b\u300b\u4e2d\u7ecf\u5e38\u4f1a\u770b\u5230accept(socket, (struct sockaddr *)&saddr_c, &lenth)\u4e4b\u7c7b\u7684\u8bed\u53e5\u5728&saddr_c\u4e4b\u524d\u9700\u8981\u589e\u52a0\u4ee3\u7801(struct sockaddr *)\u662f\u56e0\u4e3a\u5f53\u6b64\u51fd\u6570\u88ab\u8bbe\u8ba1\u7684\u65f6\u5019ANSI C\u8fd8\u6ca1\u6709\u63d0\u51favoid*\u7684\u6982\u5ff5\u3002\u6240\u6709\u7684\u5730\u5740\u7edf\u4e00\u7528struct sockaddr\u7c7b\u578b\u6807\u8bc6\uff0c\u8be5\u51fd\u6570\u7684\u7b2c\u4e8c\u4e2a\u53c2\u6570\u4e5f\u662f\u6307\u5411struct sockaddr\u7c7b\u578b\u7684\u6307\u9488\uff0c\u6b64\u5904\u662f\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u3002<\/p>\n
\u5f53\u7136\uff0c\u5728\u67d0\u4e9b\u7f16\u8bd1\u5668\u4e2d\u4e0d\u540c\u7c7b\u578b\u7684\u6307\u9488\u4e5f\u53ef\u4ee5\u8fdb\u884c\u76f4\u63a5\u8d4b\u503c\uff0c\u4f46\u4e00\u822c\u60c5\u51b5\u4e0b\u4f1a\u7ed9\u51fa\u7c7b\u578b\u4e0d\u5339\u914d\u7684\u8b66\u544a\u3002\u8981\u6c42\u7a0b\u5e8f\u5458\u663e\u793a\u7684\u7ed9\u51fa\u6307\u9488\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u53ef\u4ee5\u63d0\u9192\u7a0b\u5e8f\u5458\u5c0f\u5fc3\u4f7f\u7528\u6307\u9488\uff0c\u5bf9\u4e8e\u660e\u786e\u7a0b\u5e8f\u76ee\u7684\u5177\u6709\u4e00\u5b9a\u7684\u597d\u5904\u3002<\/p>\n
1\u3001\u6307\u9488\u7c7b\u578b\u5f3a\u5236\u8f6c\u6362\uff1a<\/p>\n
int m;\n\nint *pm = &m;\n\nchar *cp = (char *)&m;\n<\/code><\/pre>\n
pm\u6307\u5411\u4e00\u4e2a\u6574\u578b\uff0ccp\u6307\u5411\u6574\u578b\u6570\u7684\u7b2c\u4e00\u4e2a\u5b57\u8282<\/p>\n
2\u3001\u7ed3\u6784\u4f53\u4e4b\u95f4\u7684\u5f3a\u5236\u8f6c\u6362<\/p>\n
struct str1 a;\n\nstruct str2 b;\n\na=(struct str1) b;                  \/\/this is wrong\n\na=*((struct str1*)&b);         \/\/this is correct\n<\/code><\/pre>\n
3\u3001\u5173\u4e8e\u4e00\u4e2a\u7a0b\u5e8f\u7684\u89e3\u91ca<\/p>\n
 <\/p>\n
int main(void)\n\n{\n    int a[4] = {1, 2, 3, 4};\n\n    int *ptr1=(int *)(&a+1);\n\n    int *ptr2=(int *)((int)a+1);\n\n    int *c = *(a + 1);\n\n    printf("%x, %x,%x\\n", ptr1[-1], *ptr2,*c);\n\n    return 0;\n\n}\n<\/code><\/pre>\n
\u8f93\u51fa\u5206\u522b\u4e3a4 \u548c2000000,2\n\u5f0f\u5b50&a+1\u8868\u793a\u7684\u662f\u6307\u9488\u52a0\u6cd5\u8fd0\u7b97\uff0c\u800c\u4e0d\u662f\u666e\u901a\u7684\u6570\u503c\u52a0\u6cd5\u8fd0\u7b97\nvs2008\u4e0b\uff0c\u5176\u4e2da = 0x001bfc18\n(&a + 1) = 0x001bfc28\n\u800c a+1 = 0x001bfc1c<\/p>\n
&a + 1 \u7684\u503c\u53d6\u51b3\u4e8ea\u7684\u7c7b\u578b\u5982\u679ca\u7533\u660eint a;\n\u5219&a + 1 = 0xFFFF5704  = a + 1\n\u5982\u679c int a(ArryLen);\n\u5219&a + 1 = 0xFFFF5700 + 4 * ArryLen <> a + 1\na \u8868\u793a\u6570\u7ec4\u7684\u8d77\u59cb\u5730\u5740\uff0c\uff08int \uff09 a \u8868\u793a\u5c06a\u7684\u5730\u5740\u8f6c\u5316\u4e3a\u4e00\u4e2a\u6574\u5f62\u6570\uff0c\uff08int\uff09a + 1 \u8868\u793a\u666e\u901a\u7684\u6570\u503c\u52a0\u6cd5\u8fd0\u7b97\uff0c\uff08int *\uff09\uff08\uff08int\uff09a + 1\uff09\u8868\u793a\u628a\uff08int \uff09a + 1\u8f6c\u5316\u4e3a\u6574\u578b\u6307\u9488\u7684\u5730\u5740\u3002\u8be5\u5730\u5740\u6307\u5411\u6570\u7ec4a\uff080\uff09\u7684\u7b2c\u4e00\u4e2a\u5b57\u8282\uff08\u4ece0\u8ba1\u6570\uff09\uff0c\u56e0\u4e3a\u662fint\u578b\u7684 \u6240\u4ee5\u9700\u8981\u56db\u4e2a\u5b57\u8282\u7684\u89e3\u91ca\uff0c\u6240\u4ee5\u7ed3\u679c\u662fa\uff080\uff09\u7684\u540e\u4e09\u4e2a\u5b57\u8282\u548ca\uff081\uff09\u7684\u7b2c\u4e00\u4e2a\u5b57\u8282\u7ec4\u6210\u7684\u503c\uff0c\u8be5\u503c\u53d7\u5927\u5c0f\u7aef\u7684\u5f71\u54cd\u3002<\/p>\n
 *(a + 1)  \u6b64\u65f6\u7684a\u5df2\u7ecf\u662f\u4e00\u4e2a\u5e38\u6307\u9488\u4e86\uff0c\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u8ba1\u7b97\u51faa\u6240\u6307\u5411\u5143\u7d20\u540e\u9762\u7684\u7b2c2\u4e2a\u5143\u7d20\u7684\u5730\u5740\uff0c\u7136\u540e\u5bf9\u5b83\u89e3\u5f15\u7528\u5f97\u5230\u76f8\u5e94\u7684\u503c\u3002\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u7b49\u4ef7\u4e8e<\/p>\n
int last = a[1]<\/p>\n
\uff08\u8f6c\u81ea\uff1ahttps:\/\/blog.csdn.net\/mhjcumt\/article\/details\/7355127<\/a>\uff09<\/p>\n\n
 <\/p>\n
 <\/p>\n
 <\/p>\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"
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