{"id":112,"date":"2013-05-18T17:40:50","date_gmt":"2013-05-18T09:40:50","guid":{"rendered":"http:\/\/www.datarelab.com\/blog\/?p=112"},"modified":"2013-05-18T17:40:50","modified_gmt":"2013-05-18T09:40:50","slug":"%e8%ae%a4%e8%af%86%ef%bc%88%e5%a4%a7%e7%ab%af--%e5%b0%8f%e7%ab%af%ef%bc%89%e7%ab%af%e6%a8%a1%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/www.datarelab.com\/blog\/Technical_literature\/112.html","title":{"rendered":"\u8ba4\u8bc6\uff08\u5927\u7aef--\u5c0f\u7aef\uff09\u7aef\u6a21\u5f0f"},"content":{"rendered":"

    <\/span>\u7aef\u6a21\u5f0f\uff08Endian\uff09\u7684\u8fd9\u4e2a\u8bcd\u51fa\u81eaJonathan Swift\u4e66\u5199\u7684\u300a\u683c\u5217\u4f5b\u6e38\u8bb0\u300b\u3002\u8fd9\u672c\u4e66\u6839\u636e\u5c06\u9e21\u86cb\u6572\u5f00\u7684\u65b9\u6cd5\u4e0d\u540c\u5c06\u6240\u6709\u7684\u4eba\u5206\u4e3a\u4e24\u7c7b\uff0c\u4ece\u5706\u5934\u5f00\u59cb\u5c06\u9e21\u86cb\u6572\u5f00\u7684\u4eba\u88ab\u5f52\u4e3aBig Endian\uff0c\u4ece\u5c16\u5934\u5f00\u59cb\u5c06\u9e21\u86cb\u6572\u5f00\u7684\u4eba\u88ab\u5f52\u4e3aLittile Endian\u3002\u5c0f\u4eba\u56fd\u7684\u5185\u6218\u5c31\u6e90\u4e8e\u5403\u9e21\u86cb\u65f6\u662f\u7a76\u7adf\u4ece\u5927\u5934\uff08Big<\/span>-<\/span>Endian\uff09\u6572\u5f00\u8fd8\u662f\u4ece\u5c0f\u5934\uff08Little<\/span>-<\/span>Endian\uff09\u6572\u5f00\u3002\u5728\u8ba1\u7b97\u673a\u4e1aBig Endian\u548cLittle Endian\u4e5f\u51e0\u4e4e\u5f15\u8d77\u4e00\u573a\u6218\u4e89\u3002\u5728\u8ba1\u7b97\u673a\u4e1a\u754c\uff0cEndian\u8868\u793a\u6570\u636e\u5728\u5b58\u50a8\u5668\u4e2d\u7684\u5b58\u653e\u987a\u5e8f\u3002\u4e0b\u6587\u4e3e\u4f8b\u8bf4\u660e\u5728\u8ba1\u7b97\u673a\u4e2d\u5927\u5c0f\u7aef\u6a21\u5f0f\u7684\u533a\u522b\u3002<\/span>
\n    \u5982\u679c\u5c06\u4e00\u4e2a32\u4f4d\u7684\u6574\u65700x12345678\u5b58\u653e\u5230\u4e00\u4e2a\u6574\u578b\u53d8\u91cf\uff08int\uff09\u4e2d\uff0c\u8fd9\u4e2a\u6574\u578b\u53d8\u91cf\u91c7\u7528\u5927\u7aef\u6216\u8005\u5c0f\u7aef\u6a21\u5f0f\u5728\u5185\u5b58\u4e2d\u7684\u5b58\u50a8\u7531\u4e0b\u8868\u6240\u793a\u3002\u4e3a\u7b80\u5355\u8d77\u89c1\uff0c\u8fd9\u91cc\u4f7f\u7528OP0\u8868\u793a\u4e00\u4e2a32\u4f4d\u6570\u636e\u7684\u6700\u9ad8\u5b57\u8282MSB\uff08Most Significant Byte\uff09\uff0c\u4f7f\u7528OP3\u8868\u793a\u4e00\u4e2a32\u4f4d\u6570\u636e\u6700\u4f4e\u5b57\u8282LSB\uff08Least Significant Byte\uff09\u3002<\/span>
\n <\/span>
\n\u5730\u5740\u504f\u79fb   \u5927\u7aef\u6a21\u5f0f    \u5c0f\u7aef\u6a21\u5f0f <\/span>
\n0x00      12\uff08OP0\uff09   78\uff08OP3\uff09 <\/span>
\n0x01      34\uff08OP1\uff09   56\uff08OP2\uff09 <\/span>
\n0x02      56\uff08OP2\uff09   34\uff08OP1\uff09 <\/span>
\n0x03      78\uff08OP3\uff09   12\uff08OP0\uff09 <\/span>
\n    \u5982\u679c\u5c06\u4e00\u4e2a16\u4f4d\u7684\u6574\u65700x1234\u5b58\u653e\u5230\u4e00\u4e2a\u77ed\u6574\u578b\u53d8\u91cf\uff08short\uff09\u4e2d\u3002\u8fd9\u4e2a\u77ed\u6574\u578b\u53d8\u91cf\u5728\u5185\u5b58\u4e2d\u7684\u5b58\u50a8\u5728\u5927\u5c0f\u7aef\u6a21\u5f0f\u7531\u4e0b\u8868\u6240\u793a\u3002 <\/span>
\n\u5730\u5740\u504f\u79fb    \u5927\u7aef\u6a21\u5f0f    \u5c0f\u7aef\u6a21\u5f0f <\/span>
\n0x00       12\uff08OP0\uff09   34\uff08OP1\uff09 <\/span>
\n0x01       34\uff08OP1\uff09   12\uff08OP0\uff09 <\/span>
\n    \u7531\u4e0a\u8868\u6240\u77e5\uff0c\u91c7\u7528\u5927\u5c0f\u6a21\u5f0f\u5bf9\u6570\u636e\u8fdb\u884c\u5b58\u653e\u7684\u4e3b\u8981\u533a\u522b\u5728\u4e8e\u5728\u5b58\u653e\u7684\u5b57\u8282\u987a\u5e8f\uff0c\u5927\u7aef\u65b9\u5f0f\u5c06\u9ad8\u4f4d\u5b58\u653e\u5728\u4f4e\u5730\u5740\uff0c\u5c0f\u7aef\u65b9\u5f0f\u5c06\u4f4e\u4f4d\u5b58\u653e\u5728\u4f4e\u5730\u5740\u3002\u91c7\u7528\u5927\u7aef\u65b9\u5f0f\u8fdb\u884c\u6570\u636e\u5b58\u653e\u7b26\u5408\u4eba\u7c7b\u7684\u6b63\u5e38\u601d\u7ef4\uff0c\u800c\u91c7\u7528\u5c0f\u7aef\u65b9\u5f0f\u8fdb\u884c\u6570\u636e\u5b58\u653e\u5229\u4e8e\u8ba1\u7b97\u673a\u5904\u7406\u3002\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u91c7\u7528\u5927\u7aef\u6216\u8005\u5c0f\u7aef\u8fdb\u884c\u6570\u636e\u5b58\u653e\uff0c\u5176\u5b70\u4f18\u5b70\u52a3\u4e5f\u6ca1\u6709\u5b9a\u8bba\u3002<\/span>
\n    \u6709\u7684\u5904\u7406\u5668\u7cfb\u7edf\u91c7\u7528\u4e86\u5c0f\u7aef\u65b9\u5f0f\u8fdb\u884c\u6570\u636e\u5b58\u653e\uff0c\u5982Intel\u7684\u5954\u817e\u3002\u6709\u7684\u5904\u7406\u5668\u7cfb\u7edf\u91c7\u7528\u4e86\u5927\u7aef\u65b9\u5f0f\u8fdb\u884c\u6570\u636e\u5b58\u653e\uff0c\u5982IBM\u534a\u5bfc\u4f53\u548cFreescale\u7684PowerPC\u5904\u7406\u5668\u3002\u4e0d\u4ec5\u5bf9\u4e8e\u5904\u7406\u5668\uff0c\u4e00\u4e9b\u5916\u8bbe\u7684\u8bbe\u8ba1\u4e2d\u4e5f\u5b58\u5728\u7740\u4f7f\u7528\u5927\u7aef\u6216\u8005\u5c0f\u7aef\u8fdb\u884c\u6570\u636e\u5b58\u653e\u7684\u9009\u62e9\u3002<\/span>
\n    \u56e0\u6b64\u5728\u4e00\u4e2a\u5904\u7406\u5668\u7cfb\u7edf\u4e2d\uff0c\u6709\u53ef\u80fd\u5b58\u5728\u5927\u7aef\u548c\u5c0f\u7aef\u6a21\u5f0f\u540c\u65f6\u5b58\u5728\u7684\u73b0\u8c61\u3002\u8fd9\u4e00\u73b0\u8c61\u4e3a\u7cfb\u7edf\u7684\u8f6f\u786c\u4ef6\u8bbe\u8ba1\u5e26\u6765\u4e86\u4e0d\u5c0f\u7684\u9ebb\u70e6\uff0c\u8fd9\u8981\u6c42\u7cfb\u7edf\u8bbe\u8ba1\u5de5\u7a0b\u5e08\uff0c\u5fc5\u987b\u6df1\u5165\u7406\u89e3\u5927\u7aef\u548c\u5c0f\u7aef\u6a21\u5f0f\u7684\u5dee\u522b\u3002\u5927\u7aef\u4e0e\u5c0f\u7aef\u6a21\u5f0f\u7684\u5dee\u522b\u4f53\u73b0\u5728\u4e00\u4e2a\u5904\u7406\u5668\u7684\u5bc4\u5b58\u5668\uff0c\u6307\u4ee4\u96c6\uff0c\u7cfb\u7edf\u603b\u7ebf\u7b49\u5404\u4e2a\u5c42\u6b21\u4e2d\u3002<\/span><\/span> <\/p>\n

\n\t\u5224\u65ad\u5927\u7aef\u5c0f\u7aef<\/span>\n<\/p>\n

\n

\n\t\t    int i=1;  <\/span>
\n    char *p=(char *)&i;  <\/span>
\n    if(*p==1)    <\/span>
\n           printf(\"1\"); <\/span>
\n    else<\/span>
\n           printf(\"2\");<\/span>\n\t<\/p>\n

\n\t\t    <\/span><\/span><\/span>\u5927\u5c0f\u7aef\u5b58\u50a8\u95ee\u9898\uff0c\u5982\u679c\u5c0f\u7aef\u65b9\u5f0f\u4e2d\uff08i\u5360\u81f3\u5c11\u4e24\u4e2a\u5b57\u8282\u7684\u957f\u5ea6\uff09\u5219i\u6240\u5206\u914d\u7684\u5185\u5b58\u6700\u5c0f\u5730\u5740\u90a3\u4e2a\u5b57\u8282\u4e2d\u5c31\u5b58\u77401\uff0c\u5176\u4ed6\u5b57\u8282\u662f0.\u5927\u7aef\u7684\u8bdd\u52191\u5728i\u7684\u6700\u9ad8\u5730\u5740\u5b57\u8282\u5904\u5b58\u653e\uff0cchar\u662f\u4e00\u4e2a\u5b57\u8282\uff0c\u6240\u4ee5\u5f3a\u5236\u5c06char\u578b\u91cfp\u6307\u5411i\u5219p\u6307\u5411\u7684\u4e00\u5b9a\u662fi\u7684\u6700\u4f4e\u5730\u5740\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u5224\u65adp\u4e2d\u7684\u503c\u662f\u4e0d\u662f1\u6765\u786e\u5b9a\u662f\u4e0d\u662f\u5c0f\u7aef\u3002<\/span><\/span><\/span>\n\t<\/p>\n

\n\t\t\u8bf7\u5199\u4e00\u4e2aC\u51fd\u6570\uff0c\u82e5\u5904\u7406\u5668\u662fBig_endian\u7684\uff0c\u5219\u8fd4\u56de0\uff1b\u82e5\u662fLittle_endian\u7684\uff0c\u5219\u8fd4\u56de1<\/span>\n\t<\/div>\n
\n\t\t\u89e3\u7b54\uff1a<\/span>\n\t<\/div>\n
\n\t\tint checkCPU( )<\/span>\n\t<\/div>\n
\n\t\t{<\/span>\n\t<\/div>\n
\n\t\t    {<\/span>\n\t<\/div>\n
\n\t\t     union w<\/span>\n\t<\/div>\n
\n\t\t      {  <\/span>\n\t<\/div>\n
\n\t\t         int a;<\/span>\n\t<\/div>\n
\n\t\t         char b;<\/span>\n\t<\/div>\n
\n\t\t      } c;<\/span>\n\t<\/div>\n
\n\t\t      c.a = 1;<\/span>\n\t<\/div>\n
\n\t\t      return(c.b ==1);<\/span>\n\t<\/div>\n
\n\t\t    }<\/span>\n\t<\/div>\n
\n\t\t}<\/span>\n\t<\/div>\n
\n\t\t\u5256\u6790\uff1a<\/span>\n\t<\/div>\n
\n\t\t    <\/span>\u5d4c\u5165\u5f0f\u7cfb\u7edf\u5f00\u53d1\u8005\u5e94\u8be5\u5bf9Little-endian\u548cBig-endian\u6a21\u5f0f\u975e\u5e38\u4e86\u89e3\u3002\u91c7\u7528Little-endian\u6a21\u5f0f\u7684CPU\u5bf9\u64cd\u4f5c\u6570\u7684\u5b58\u653e\u65b9\u5f0f\u662f\u4ece\u4f4e\u5b57\u8282\u5230\u9ad8\u5b57\u8282\uff0c\u800cBig-endian\u6a21\u5f0f\u5bf9\u64cd\u4f5c\u6570\u7684\u5b58\u653e\u65b9\u5f0f\u662f\u4ece\u9ad8\u5b57\u8282\u5230\u4f4e\u5b57\u8282\u3002\u4f8b\u5982\uff0c16bit\u5bbd\u7684\u65700x1234\u5728Little-endian\u6a21\u5f0fCPU\u5185\u5b58\u4e2d\u7684\u5b58\u653e\u65b9\u5f0f\uff08\u5047\u8bbe\u4ece\u5730\u57400x4000\u5f00\u59cb\u5b58\u653e\uff09\u4e3a\uff1a<\/span>\n\t<\/div>\n
\n\t\t <\/span>\n\t<\/div>\n
\n\n\n\n\n
\n\t\t\t\t\t\t\u5185\u5b58\u5730\u5740<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4000<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4001<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n
\n\t\t\t\t\t\t\u5b58\u653e\u5185\u5bb9<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x34<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x12<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n
\n\t\t\u800c\u5728<\/span>Big-endian<\/span>\u6a21\u5f0f<\/span>CPU<\/span><\/span><\/span>\u5185\u5b58\u4e2d\u7684\u5b58\u653e\u65b9\u5f0f\u5219\u4e3a<\/span>\uff1a<\/span><\/span>\n\t<\/div>\n
\n\n\n\n\n
\n\t\t\t\t\t\t\u5185\u5b58\u5730\u5740<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4000<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4001<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n
\n\t\t\t\t\t\t\u5b58\u653e\u5185\u5bb9<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x12<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x34<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n
\n\t\t32bit<\/span>\u5bbd\u7684\u6570<\/span>0x12345678<\/span>\u5728<\/span>Little-endian<\/span>\u6a21\u5f0f<\/span>CPU<\/span>\u5185\u5b58\u4e2d\u7684\u5b58\u653e\u65b9\u5f0f\uff08\u5047\u8bbe\u4ece\u5730\u5740<\/span>0x4000<\/span>\u5f00\u59cb\u5b58\u653e\uff09\u4e3a\uff1a<\/span>\n\t<\/div>\n
\n\n\n\n\n
\n\t\t\t\t\t\t\u5185\u5b58\u5730\u5740<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4000<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4001<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4002<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4003<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n
\n\t\t\t\t\t\t\u5b58\u653e\u5185\u5bb9<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x78<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x56<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x34<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x12<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n
\n\t\t\u800c\u5728<\/span>Big-endian<\/span>\u6a21\u5f0f<\/span>CPU<\/span>\u5185\u5b58\u4e2d\u7684\u5b58\u653e\u65b9\u5f0f\u5219\u4e3a\uff1a<\/span>\n\t<\/div>\n
\n\n\n\n\n
\n\t\t\t\t\t\t\u5185\u5b58\u5730\u5740<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4000<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4001<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4002<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x4003<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n
\n\t\t\t\t\t\t\u5b58\u653e\u5185\u5bb9<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x12<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x34<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x56<\/span>\n\t\t\t\t\t<\/td>\n\n\t\t\t\t\t\t0x78<\/span>\n\t\t\t\t\t<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n
\n\t\t\u8054\u5408\u4f53<\/span>union<\/span>\u7684\u5b58\u653e\u987a\u5e8f\u662f\u6240\u6709\u6210\u5458\u90fd\u4ece\u4f4e\u5730\u5740\u5f00\u59cb\u5b58\u653e\uff0c\u9762\u8bd5\u8005\u7684\u89e3\u7b54\u5229\u7528\u8be5\u7279\u6027\uff0c\u8f7b\u677e\u5730\u83b7\u5f97\u4e86<\/span>CPU<\/span>\u5bf9\u5185\u5b58\u91c7\u7528<\/span>Little-endian<\/span>\u8fd8\u662f<\/span>Big-endian<\/span>\u6a21\u5f0f\u8bfb\u5199\u3002<\/span>\n\t<\/div>\n<\/div>\n

<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

    \u7aef\u6a21\u5f0f\uff08Endian\uff09\u7684\u8fd9\u4e2a\u8bcd\u51fa\u81eaJonathan Swift\u4e66\u5199\u7684\u300a\u683c […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-112","post","type-post","status-publish","format-standard","hentry","category-Technical_literature"],"views":1381,"_links":{"self":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts\/112","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/comments?post=112"}],"version-history":[{"count":0,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts\/112\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/media?parent=112"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/categories?post=112"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/tags?post=112"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}