{"id":97516,"date":"2026-08-29T18:40:43","date_gmt":"2026-08-29T10:40:43","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/97516.html"},"modified":"2026-08-29T18:40:43","modified_gmt":"2026-08-29T10:40:43","slug":"c-%e8%af%ad%e8%a8%80%e8%bf%b7%e4%bd%a0%e6%97%a5%e5%bf%97%e7%b3%bb%e7%bb%9f%ef%bc%9a%e6%a0%87%e5%87%86-io-%e5%ae%9e%e7%8e%b0%e6%97%a5%e5%bf%97%e6%9f%a5%e8%af%a2%e3%80%81%e7%ad%9b%e9%80%89%e4%b8%8e","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/97516.html","title":{"rendered":"C \u8bed\u8a00\u8ff7\u4f60\u65e5\u5fd7\u7cfb\u7edf\uff1a\u6807\u51c6 IO \u5b9e\u73b0\u65e5\u5fd7\u67e5\u8be2\u3001\u7b5b\u9009\u4e0e\u7edf\u8ba1 | \u9644\u6838\u5fc3\u77e5\u8bc6\u70b9\u8be6\u89e3"},"content":{"rendered":"<\/p>\n<h4>\u6587\u7ae0\u76ee\u5f55<\/h4>\n<ul>\n<li>\u524d\u8a00<\/li>\n<li>\u4e00\u3001\u9879\u76ee\u6574\u4f53\u67b6\u6784\u4e0e\u4e3b\u51fd\u6570\u8bbe\u8ba1\n<ul>\n<li>1.1 \u547d\u4ee4\u884c\u53c2\u6570 argc\/argv<\/li>\n<li>1.2 main \u51fd\u6570\u5206\u53d1\u903b\u8f91<\/li>\n<\/ul>\n<\/li>\n<li>\u4e8c\u3001\u6807\u51c6 IO vs \u7cfb\u7edf\u8c03\u7528&#xff1a;\u4e3a\u4ec0\u4e48 fgets \u7b80\u5316\u4e86\u884c\u8bfb\u53d6\n<ul>\n<li>2.1 \u539f\u751f read \u7684\u75db\u70b9&#xff1a;\u534a\u884c\u622a\u65ad\u95ee\u9898<\/li>\n<li>2.2 fgets \u7684\u4f18\u52bf&#xff1a;\u539f\u751f\u652f\u6301\u6309\u884c\u8bfb\u53d6<\/li>\n<li>2.3 \u4e24\u5957 API \u5bf9\u5e94\u5173\u7cfb<\/li>\n<\/ul>\n<\/li>\n<li>\u4e09\u3001\u6838\u5fc3\u5b57\u7b26\u4e32\u51fd\u6570\u8be6\u89e3\n<ul>\n<li>3.1 strcmp&#xff1a;\u5b57\u7b26\u4e32\u76f8\u7b49\u5224\u65ad<\/li>\n<li>3.2 strstr&#xff1a;\u5b50\u4e32\u67e5\u627e<\/li>\n<li>3.3 strtok&#xff1a;\u5b57\u7b26\u4e32\u5206\u5272<\/li>\n<\/ul>\n<\/li>\n<li>\u56db\u3001\u4e09\u5927\u529f\u80fd\u6a21\u5757\u5b8c\u6574\u5b9e\u73b0\n<ul>\n<li>4.1 \u65e5\u5fd7\u5217\u8868\u5c55\u793a log_list<\/li>\n<li>4.2 \u6309\u7b49\u7ea7\u7b5b\u9009\u65e5\u5fd7 log_find<\/li>\n<li>4.3 \u65e5\u5fd7\u7b49\u7ea7\u7edf\u8ba1 log_count<\/li>\n<\/ul>\n<\/li>\n<li>\u4e94\u3001\u9ad8\u9891\u8e29\u5751\u70b9\u603b\u7ed3<\/li>\n<li>\u516d\u3001\u8fd0\u884c\u6548\u679c\u6f14\u793a<\/li>\n<li>\u603b\u7ed3<\/li>\n<\/ul>\n<hr \/>\n<h2><\/h2>\n<h3>\u524d\u8a00<\/h3>\n<p>\u5728\u4e0a\u4e00\u7bc7\u4e2d\u6211\u4eec\u57fa\u4e8e open\/write \u7cfb\u7edf\u8c03\u7528\u5b8c\u6210\u4e86\u65e5\u5fd7\u5199\u5165\u529f\u80fd&#xff0c;\u672c\u7bc7\u6211\u4eec\u7ee7\u7eed\u5b8c\u5584\u65e5\u5fd7\u7cfb\u7edf\u7684\u67e5\u8be2\u3001\u7b5b\u9009\u3001\u7edf\u8ba1\u4e09\u5927\u6838\u5fc3\u529f\u80fd\u3002 \u5f88\u591a\u540c\u5b66\u4f1a\u56f0\u60d1&#xff1a;\u4e3a\u4ec0\u4e48\u624b\u5199 read \u8bfb\u53d6\u65e5\u5fd7\u8981\u5199\u590d\u6742\u7684 leftover \u6b8b\u7559\u7f13\u51b2\u533a&#xff1f;\u6362\u6210 C \u6807\u51c6 IO \u7684 fgets \u4e3a\u4ec0\u4e48\u5c31\u80fd\u5927\u5e45\u7b80\u5316\u4ee3\u7801&#xff1f;\u672c\u6587\u4f1a\u4ece\u5e95\u5c42\u539f\u7406\u5230\u4ee3\u7801\u5b9e\u73b0\u4e00\u6b65\u6b65\u62c6\u89e3&#xff0c;\u540c\u65f6\u68b3\u7406 strtok\/strcmp\/strstr \u7b49\u9ad8\u9891\u5b57\u7b26\u4e32\u51fd\u6570\u7684\u7528\u6cd5\u4e0e\u5751\u70b9\u3002<\/p>\n<hr \/>\n<h3>\u4e00\u3001\u9879\u76ee\u6574\u4f53\u67b6\u6784\u4e0e\u4e3b\u51fd\u6570\u8bbe\u8ba1<\/h3>\n<p>\u6574\u4e2a\u65e5\u5fd7\u7a0b\u5e8f\u901a\u8fc7\u547d\u4ee4\u884c\u53c2\u6570\u9a71\u52a8&#xff0c;\u652f\u6301 write\/list\/find\/count\/help \u4e94\u4e2a\u5b50\u547d\u4ee4&#xff0c;\u4e3b\u51fd\u6570\u8d1f\u8d23\u53c2\u6570\u6821\u9a8c\u4e0e\u529f\u80fd\u5206\u53d1&#xff0c;\u662f\u6574\u4e2a\u7a0b\u5e8f\u7684\u5165\u53e3\u8c03\u5ea6\u4e2d\u5fc3\u3002<\/p>\n<h4>1.1 \u547d\u4ee4\u884c\u53c2\u6570 argc\/argv<\/h4>\n<p>C \u8bed\u8a00\u4e3b\u51fd\u6570\u7684\u4e24\u4e2a\u53c2\u6570\u662f\u547d\u4ee4\u884c\u7f16\u7a0b\u7684\u57fa\u7840&#xff1a;<\/p>\n<p>int main(int argc, char* argv[])<\/p>\n<ul>\n<li>argc&#xff1a;\u53c2\u6570\u603b\u4e2a\u6570&#xff0c;\u7a0b\u5e8f\u540d\u672c\u8eab\u7b97\u7b2c 0 \u4e2a\u53c2\u6570<\/li>\n<li>argv&#xff1a;\u5b57\u7b26\u4e32\u6307\u9488\u6570\u7ec4&#xff0c;\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u547d\u4ee4\u884c\u53c2\u6570\n<ul>\n<li>argv[0]&#xff1a;\u7a0b\u5e8f\u672c\u8eab\u8def\u5f84&#xff0c;\u5982 .\/minilog<\/li>\n<li>argv[1]&#xff1a;\u5b50\u547d\u4ee4&#xff0c;\u5982 write\/list\/find<\/li>\n<li>argv[2]\/argv[3]&#xff1a;\u5b50\u547d\u4ee4\u7684\u9644\u52a0\u53c2\u6570<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u4e3e\u4e2a\u4f8b\u5b50&#xff0c;\u6267\u884c .\/minilog write INFO &#034;system start&#034;&#xff1a;<\/p>\n<ul>\n<li>argc &#061; 4<\/li>\n<li>argv[0] &#061; &#034;.\/minilog&#034;&#xff0c;argv[1] &#061; &#034;write&#034;&#xff0c;argv[2] &#061; &#034;INFO&#034;&#xff0c;argv[3] &#061; &#034;system start&#034;<\/li>\n<\/ul>\n<h4>1.2 main \u51fd\u6570\u5206\u53d1\u903b\u8f91<\/h4>\n<p>\u4e3b\u51fd\u6570\u91c7\u7528\u300c\u5148\u6821\u9a8c\u53c2\u6570&#xff0c;\u518d\u5206\u652f\u5339\u914d\u547d\u4ee4\u300d\u7684\u7ed3\u6784&#xff0c;\u7528 strcmp \u5339\u914d\u7528\u6237\u8f93\u5165\u7684\u5b50\u547d\u4ee4&#xff0c;\u5206\u53d1\u5230\u5bf9\u5e94\u529f\u80fd\u51fd\u6570&#xff1a;<\/p>\n<p>int main(int argc, char* argv[])<br \/>\n{<br \/>\n    \/\/ \u53c2\u6570\u8fc7\u5c11&#xff1a;\u6253\u5370\u5e2e\u52a9\u9000\u51fa<br \/>\n    if (argc &lt; 2) {<br \/>\n        fprintf(stderr, &#034;Error: missing command\\\\n&#034;);<br \/>\n        print_help();<br \/>\n        return 1;<br \/>\n    }<br \/>\nconst char* cmd &#061; argv[1];<\/p>\n<p>\/\/ \u5199\u65e5\u5fd7\u547d\u4ee4<br \/>\nif (0 &#061;&#061; strcmp(cmd, &#034;write&#034;)) {<br \/>\n    if (argc !&#061; 4) {<br \/>\n        fprintf(stderr, &#034;Error: bad arguments for write\\\\n&#034;);<br \/>\n        return 1;<br \/>\n    }<br \/>\n    return do_write(argv) &#061;&#061; 0 ? 0 : 1;<br \/>\n}<br \/>\n\/\/ \u67e5\u770b\u5168\u90e8\u65e5\u5fd7<br \/>\nelse if (0 &#061;&#061; strcmp(cmd, &#034;list&#034;)) {<br \/>\n    return log_list(FILENAME) &#061;&#061; 0 ? 0 : 1;<br \/>\n}<br \/>\n\/\/ \u6309\u7b49\u7ea7\u7b5b\u9009\u65e5\u5fd7<br \/>\nelse if (0 &#061;&#061; strcmp(cmd, &#034;find&#034;)) {<br \/>\n    if (argc !&#061; 3) {<br \/>\n        fprintf(stderr, &#034;Error: missing level for find\\\\n&#034;);<br \/>\n        return 1;<br \/>\n    }<br \/>\n    return log_find(FILENAME, argv[2]) &#061;&#061; 0 ? 0 : 1;<br \/>\n}<br \/>\n\/\/ \u7edf\u8ba1\u65e5\u5fd7\u6570\u91cf<br \/>\nelse if (0 &#061;&#061; strcmp(cmd, &#034;count&#034;)) {<br \/>\n    return log_count(FILENAME) &#061;&#061; 0 ? 0 : 1;<br \/>\n}<br \/>\n\/\/ \u6253\u5370\u5e2e\u52a9<br \/>\nelse if (0 &#061;&#061; strcmp(cmd, &#034;help&#034;)) {<br \/>\n    print_help();<br \/>\n    return 0;<br \/>\n}<br \/>\n\/\/ \u672a\u77e5\u547d\u4ee4<br \/>\nelse {<br \/>\n    fprintf(stderr, &#034;Error: unknown command &#039;%s&#039;\\\\n&#034;, cmd);<br \/>\n    print_help();<br \/>\n    return 1;<br \/>\n}<br \/>\n} <\/p>\n<p>\u8bbe\u8ba1\u7ec6\u8282&#xff1a;<\/p>\n<ul>\n<li>\u5e38\u91cf\u5de6\u5199 0 &#061;&#061; strcmp(&#8230;)&#xff1a;\u907f\u514d\u624b\u8bef\u5199\u6210 &#061; \u8d4b\u503c\u5bfc\u81f4\u7684\u9690\u853d bug<\/li>\n<li>\u7edf\u4e00\u8fd4\u56de\u503c\u89c4\u8303&#xff1a;\u51fd\u6570\u8fd4\u56de 0 \u4ee3\u8868\u6210\u529f&#xff0c;\u975e 0 \u4ee3\u8868\u5931\u8d25&#xff0c;\u4e3b\u51fd\u6570\u900f\u4f20\u8fd4\u56de\u503c\u7ed9\u64cd\u4f5c\u7cfb\u7edf<\/li>\n<li>\u63d0\u524d\u6821\u9a8c\u53c2\u6570&#xff1a;\u6bcf\u4e2a\u5b50\u547d\u4ee4\u5148\u68c0\u67e5\u53c2\u6570\u4e2a\u6570\u662f\u5426\u5408\u6cd5&#xff0c;\u4e0d\u5408\u6cd5\u76f4\u63a5\u62a5\u9519\u9000\u51fa<\/li>\n<\/ul>\n<h3>\u4e8c\u3001\u6807\u51c6 IO vs \u7cfb\u7edf\u8c03\u7528&#xff1a;\u4e3a\u4ec0\u4e48 fgets \u7b80\u5316\u4e86\u884c\u8bfb\u53d6<\/h3>\n<h4>2.1 \u539f\u751f read \u7684\u75db\u70b9&#xff1a;\u534a\u884c\u622a\u65ad\u95ee\u9898<\/h4>\n<p>read \u662f POSIX \u7cfb\u7edf\u8c03\u7528&#xff0c;\u53ea\u8ba4\u5b57\u8282\u3001\u4e0d\u8ba4\u6362\u884c\u7b26&#xff0c;\u6bcf\u6b21\u6309\u56fa\u5b9a\u5927\u5c0f\u7684\u5b57\u8282\u5757\u8bfb\u53d6\u6570\u636e\u3002 \u5982\u679c\u4e00\u884c\u65e5\u5fd7\u521a\u597d\u8de8\u8d8a\u4e24\u6b21 read \u7684\u8fb9\u754c&#xff0c;\u5c31\u4f1a\u51fa\u73b0\u300c\u4e00\u884c\u65e5\u5fd7\u88ab\u5207\u6210\u4e24\u534a\u300d\u7684\u60c5\u51b5&#xff0c;\u5fc5\u987b\u624b\u52a8\u7ef4\u62a4 leftover \u6b8b\u7559\u7f13\u51b2\u533a\u4fdd\u5b58\u534a\u884c\u6570\u636e&#xff0c;\u4e0b\u4e00\u6b21\u8bfb\u53d6\u518d\u62fc\u63a5\u6210\u5b8c\u6574\u884c&#xff0c;\u4ee3\u7801\u590d\u6742\u4e14\u5bb9\u6613\u51fa bug\u3002 \u5178\u578b\u573a\u666f&#xff1a;<\/p>\n<ul>\n<li>\u6587\u4ef6\u672b\u5c3e\u6700\u540e\u4e00\u884c\u6ca1\u6709\u6362\u884c\u7b26&#xff0c;\u4f1a\u76f4\u63a5\u4e22\u5931<\/li>\n<li>\u5355\u6b21\u8bfb\u53d6\u5305\u542b\u591a\u884c\u540e&#xff0c;\u672b\u5c3e\u5269\u4f59\u7684\u534a\u884c\u4f1a\u88ab\u622a\u65ad\u4e22\u5f03<\/li>\n<\/ul>\n<h4>2.2 fgets \u7684\u4f18\u52bf&#xff1a;\u539f\u751f\u652f\u6301\u6309\u884c\u8bfb\u53d6<\/h4>\n<p>fgets \u662f C \u6807\u51c6\u5e93 &lt;stdio.h&gt; \u63d0\u4f9b\u7684\u51fd\u6570&#xff0c;\u5e95\u5c42\u4f9d\u7136\u8c03\u7528 read&#xff0c;\u4f46\u5e93\u5185\u90e8\u5df2\u7ecf\u5e2e\u6211\u4eec\u5b9e\u73b0\u4e86\u7f13\u51b2\u533a\u548c\u534a\u884c\u62fc\u63a5\u903b\u8f91&#xff0c;\u6211\u4eec\u76f4\u63a5\u5c31\u80fd\u62ff\u5230\u5b8c\u6574\u7684\u4e00\u884c&#xff1a;<\/p>\n<p>char *fgets(char *s, int size, FILE *stream);<\/p>\n<ul>\n<li>\u9047\u5230 \\\\n \u6216\u8bfb\u5230\u6587\u4ef6\u672b\u5c3e\u5c31\u505c\u6b62&#xff0c;\u81ea\u52a8\u628a\u6362\u884c\u7b26\u5b58\u5165\u7f13\u51b2\u533a<\/li>\n<li>\u81ea\u52a8\u5728\u672b\u5c3e\u8865 \\\\0&#xff0c;\u5f97\u5230\u5408\u6cd5\u7684 C \u5b57\u7b26\u4e32<\/li>\n<li>\u8fd4\u56de NULL \u4ee3\u8868\u8bfb\u5230\u6587\u4ef6\u672b\u5c3e\u6216\u8bfb\u53d6\u5931\u8d25<\/li>\n<\/ul>\n<h4>2.3 \u4e24\u5957 API \u5bf9\u5e94\u5173\u7cfb<\/h4>\n<table>\n<tr>\u529f\u80fdPOSIX \u7cfb\u7edf\u8c03\u7528C \u6807\u51c6 IO \u5e93<\/tr>\n<tbody>\n<tr>\n<td>\u6253\u5f00\u6587\u4ef6<\/td>\n<td>open()<\/td>\n<td>fopen()<\/td>\n<\/tr>\n<tr>\n<td>\u8bfb\u53d6\u6570\u636e<\/td>\n<td>read()<\/td>\n<td>fgets()\/fread()<\/td>\n<\/tr>\n<tr>\n<td>\u5199\u5165\u6570\u636e<\/td>\n<td>write()<\/td>\n<td>fwrite()\/printf()<\/td>\n<\/tr>\n<tr>\n<td>\u5173\u95ed\u6587\u4ef6<\/td>\n<td>close()<\/td>\n<td>fclose()<\/td>\n<\/tr>\n<tr>\n<td>\u53e5\u67c4\u7c7b\u578b<\/td>\n<td>int fd \u6587\u4ef6\u63cf\u8ff0\u7b26<\/td>\n<td>FILE* \u6587\u4ef6\u6d41\u6307\u9488<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u6ce8\u610f&#xff1a;\u4e24\u5957 API \u7edd\u5bf9\u4e0d\u80fd\u6df7\u7528&#xff0c;\u4e0d\u80fd\u7528 fopen \u6253\u5f00\u5374\u7528 close \u5173\u95ed\u3002<\/p>\n<h3>\u4e09\u3001\u6838\u5fc3\u5b57\u7b26\u4e32\u51fd\u6570\u8be6\u89e3<\/h3>\n<p>\u65e5\u5fd7\u89e3\u6790\u7684\u6838\u5fc3\u662f\u5b57\u7b26\u4e32\u5904\u7406&#xff0c;\u4e09\u4e2a\u51fd\u6570\u662f\u9ad8\u9891\u5fc5\u7528\u5de5\u5177&#xff0c;\u6211\u4eec\u9010\u4e2a\u62c6\u89e3\u7528\u6cd5\u548c\u907f\u5751\u70b9\u3002<\/p>\n<h4>3.1 strcmp&#xff1a;\u5b57\u7b26\u4e32\u76f8\u7b49\u5224\u65ad<\/h4>\n<p>int strcmp(const char *s1, const char *s2);<\/p>\n<ul>\n<li>\u529f\u80fd&#xff1a;\u9010\u5b57\u8282\u6bd4\u8f83\u4e24\u4e2a\u5b57\u7b26\u4e32&#xff0c;\u8fd4\u56de\u503c\u4e3a 0 \u4ee3\u8868\u5b8c\u5168\u76f8\u7b49<\/li>\n<li>\u7528\u9014&#xff1a;\u5224\u65ad\u547d\u4ee4\u662f\u5426\u5339\u914d\u3001\u5224\u65ad\u65e5\u5fd7\u7b49\u7ea7\u662f\u5426\u5339\u914d<\/li>\n<li>\u6ce8\u610f&#xff1a;\u53ea\u80fd\u6bd4\u8f83\u4ee5 \\\\0 \u7ed3\u5c3e\u7684\u5408\u6cd5 C \u5b57\u7b26\u4e32<\/li>\n<\/ul>\n<h4>3.2 strstr&#xff1a;\u5b50\u4e32\u67e5\u627e<\/h4>\n<p>char *strstr(const char *haystack, const char *needle);<\/p>\n<ul>\n<li>\u529f\u80fd&#xff1a;\u5728\u5927\u5b57\u7b26\u4e32\u4e2d\u67e5\u627e\u662f\u5426\u5305\u542b\u76ee\u6807\u5b50\u4e32<\/li>\n<li>\u8fd4\u56de\u503c&#xff1a;\u627e\u5230\u8fd4\u56de\u5b50\u4e32\u8d77\u59cb\u5730\u5740&#xff0c;\u627e\u4e0d\u5230\u8fd4\u56de NULL<\/li>\n<li>\u7528\u9014&#xff1a;\u5feb\u901f\u5224\u65ad\u4e00\u884c\u65e5\u5fd7\u4e2d\u662f\u5426\u5305\u542b\u67d0\u4e2a\u7b49\u7ea7\u6807\u7b7e<\/li>\n<\/ul>\n<p>\/\/ \u5224\u65adline\u4e2d\u662f\u5426\u5305\u542b[INFO]<br \/>\nif (strstr(line, &#034;[INFO]&#034;) !&#061; NULL) {<br \/>\n    printf(&#034;%s&#034;, line);<br \/>\n}<\/p>\n<h4>3.3 strtok&#xff1a;\u5b57\u7b26\u4e32\u5206\u5272<\/h4>\n<p>char *strtok(char *str, const char *delim);<\/p>\n<ul>\n<li>\u529f\u80fd&#xff1a;\u6309\u6307\u5b9a\u5206\u9694\u7b26\u5207\u5272\u5b57\u7b26\u4e32&#xff0c;\u7b2c\u4e00\u6b21\u4f20\u539f\u4e32&#xff0c;\u540e\u7eed\u4f20 NULL<\/li>\n<li>\u7528\u9014&#xff1a;\u628a\u4e00\u884c\u65e5\u5fd7\u6309\u7a7a\u683c\u62c6\u5206\u6210\u300c\u65e5\u671f\u3001\u65f6\u95f4\u3001\u7b49\u7ea7\u3001\u5185\u5bb9\u300d\u591a\u4e2a\u5b57\u6bb5<\/li>\n<li>\u26a0\ufe0f \u91cd\u5927\u5751\u70b9&#xff1a;strtok \u4f1a\u4fee\u6539\u539f\u5b57\u7b26\u4e32&#xff0c;\u628a\u5206\u9694\u7b26\u66ff\u6362\u6210 \\\\0&#xff0c;\u5207\u5272\u540e\u539f\u4e32\u4f1a\u88ab\u7834\u574f<\/li>\n<\/ul>\n<p>\u793a\u4f8b&#xff1a;\u62c6\u5206\u4e00\u884c\u65e5\u5fd7<\/p>\n<p>char line[] &#061; &#034;[2026-08-24 10:30:15] [INFO] system start&#034;;<br \/>\nchar *args[5] &#061; {NULL};<br \/>\nargs[0] &#061; strtok(line, &#034; &#034;);  \/\/ \u7b2c\u4e00\u6b21\u8c03\u7528\u4f20\u539f\u4e32<br \/>\nfor (int i &#061; 1; i &lt; 5; i&#043;&#043;) {<br \/>\nargs[i] &#061; strtok(NULL, &#034; &#034;); \/\/ \u540e\u7eed\u8c03\u7528\u4f20NULL<br \/>\n}<br \/>\n\/\/ args[0] &#061; &#034;[2026-08-24&#034;<br \/>\n\/\/ args[1] &#061; &#034;10:30:15]&#034;<br \/>\n\/\/ args[2] &#061; &#034;[INFO]&#034;<br \/>\n\/\/ args[3] &#061; &#034;system&#034; <\/p>\n<h3>\u56db\u3001\u4e09\u5927\u529f\u80fd\u6a21\u5757\u5b8c\u6574\u5b9e\u73b0<\/h3>\n<p>\u6211\u4eec\u7edf\u4e00\u91c7\u7528 fopen &#043; fgets &#043; \u6b7b\u5faa\u73afwhile(1) \u7684\u5199\u6cd5&#xff0c;\u5bf9\u9f50\u6807\u51c6\u4ee3\u7801\u98ce\u683c\u3002<\/p>\n<h4>4.1 \u65e5\u5fd7\u5217\u8868\u5c55\u793a log_list<\/h4>\n<p>\u6700\u7b80\u5355\u7684\u529f\u80fd&#xff0c;\u9010\u884c\u8bfb\u53d6\u6587\u4ef6\u76f4\u63a5\u8f93\u51fa\u5373\u53ef&#xff1a;<\/p>\n<p>int log_list(const char* filename)<br \/>\n{<br \/>\n    FILE *fp &#061; fopen(filename, &#034;r&#034;);<br \/>\n    if (NULL &#061;&#061; fp) {<br \/>\n        perror(&#034;log_list fopen error&#034;);<br \/>\n        return -1;<br \/>\n    }<br \/>\nchar line_buf[512];<br \/>\nwhile (1) {<br \/>\n    if (NULL &#061;&#061; fgets(line_buf, sizeof(line_buf), fp)) {<br \/>\n        break;<br \/>\n    }<br \/>\n    \/\/ fgets\u81ea\u5e26\u6362\u884c\u7b26&#xff0c;\u4e0d\u7528\u989d\u5916\u52a0\\\\n<br \/>\n    printf(&#034;%s&#034;, line_buf);<br \/>\n}<\/p>\n<p>fclose(fp);<br \/>\nreturn 0;<br \/>\n} <\/p>\n<h4>4.2 \u6309\u7b49\u7ea7\u7b5b\u9009\u65e5\u5fd7 log_find<\/h4>\n<p>\u8fd9\u91cc\u6709\u4e2a\u5173\u952e\u7ec6\u8282&#xff1a;\u4e0d\u80fd\u76f4\u63a5\u5bf9\u539f\u884c\u7528 strtok \u62c6\u5206&#xff0c;\u5426\u5219\u539f\u5b57\u7b26\u4e32\u88ab\u7834\u574f&#xff0c;\u6253\u5370\u4f1a\u6b8b\u7f3a\u3002\u6211\u4eec\u7528\u4e34\u65f6\u526f\u672c\u505a\u62c6\u5206\u5224\u65ad&#xff0c;\u539f\u884c\u4fdd\u7559\u5b8c\u6574\u5185\u5bb9\u7528\u4e8e\u8f93\u51fa\u3002<\/p>\n<p>int log_find(const char* filename, const char* level)<br \/>\n{<br \/>\n    char target[32] &#061; {0};<br \/>\n    sprintf(target, &#034;[%s]&#034;, level);<br \/>\n\/\/ \u7b49\u7ea7\u5408\u6cd5\u6027\u6821\u9a8c<br \/>\nif (0 !&#061; strcmp(target, &#034;[DEBUG]&#034;) &amp;amp;&amp;amp;<br \/>\n    0 !&#061; strcmp(target, &#034;[INFO]&#034;)  &amp;amp;&amp;amp;<br \/>\n    0 !&#061; strcmp(target, &#034;[WARN]&#034;)  &amp;amp;&amp;amp;<br \/>\n    0 !&#061; strcmp(target, &#034;[ERROR]&#034;))<br \/>\n{<br \/>\n    fprintf(stderr, &#034;Error: invalid log level &#039;%s&#039;\\\\n&#034;, level);<br \/>\n    return -1;<br \/>\n}<\/p>\n<p>FILE *fp &#061; fopen(filename, &#034;r&#034;);<br \/>\nif (NULL &#061;&#061; fp) {<br \/>\n    perror(&#034;log_find fopen error&#034;);<br \/>\n    return -1;<br \/>\n}<\/p>\n<p>int i &#061; 0;<br \/>\nwhile (1) {<br \/>\n    char *args[5] &#061; {NULL};<br \/>\n    char line_buf[512] &#061; {0};<br \/>\n    char tmp_buf[512] &#061; {0}; \/\/ \u526f\u672c&#xff1a;\u4e13\u95e8\u7528\u4e8estrtok\u62c6\u5206<\/p>\n<p>    if (NULL &#061;&#061; fgets(line_buf, sizeof(line_buf), fp)) {<br \/>\n        break;<br \/>\n    }<\/p>\n<p>    \/\/ \u62f7\u8d1d\u526f\u672c&#xff0c;\u62c6\u5206\u4e0d\u5f71\u54cd\u539f\u884c<br \/>\n    strcpy(tmp_buf, line_buf);<br \/>\n    args[0] &#061; strtok(tmp_buf, &#034; &#034;);<br \/>\n    for (i &#061; 1; i &amp;lt; 5; i&#043;&#043;) {<br \/>\n        args[i] &#061; strtok(NULL, &#034; &#034;);<br \/>\n    }<\/p>\n<p>    \/\/ \u7b49\u7ea7\u5339\u914d\u5219\u6253\u5370\u539f\u5b8c\u6574\u884c<br \/>\n    if (0 &#061;&#061; strcmp(args[2], target)) {<br \/>\n        printf(&#034;%s&#034;, line_buf);<br \/>\n    }<br \/>\n}<\/p>\n<p>fclose(fp);<br \/>\nreturn 0;<br \/>\n} <\/p>\n<h4>4.3 \u65e5\u5fd7\u7b49\u7ea7\u7edf\u8ba1 log_count<\/h4>\n<p>\u7edf\u8ba1\u529f\u80fd\u53ea\u9700\u8981\u63d0\u53d6\u7b49\u7ea7&#xff0c;\u4e0d\u9700\u8981\u4fdd\u7559\u539f\u884c\u5185\u5bb9&#xff0c;\u6240\u4ee5\u53ef\u4ee5\u76f4\u63a5\u62c6\u5206\u539f\u5b57\u7b26\u4e32&#xff1a;<\/p>\n<p>int log_count(const char* filename)<br \/>\n{<br \/>\n    FILE *fp &#061; fopen(filename, &#034;r&#034;);<br \/>\n    if (NULL &#061;&#061; fp) {<br \/>\n        perror(&#034;log_count fopen error&#034;);<br \/>\n        return -1;<br \/>\n    }<br \/>\nint count[4] &#061; {0}; \/\/ 0:DEBUG 1:INFO 2:WARN 3:ERROR<br \/>\nint i &#061; 0;<\/p>\n<p>while (1) {<br \/>\n    char *args[5] &#061; {NULL};<br \/>\n    char line_buf[512] &#061; {0};<\/p>\n<p>    if (NULL &#061;&#061; fgets(line_buf, sizeof(line_buf), fp)) {<br \/>\n        break;<br \/>\n    }<\/p>\n<p>    \/\/ \u6309\u7a7a\u683c\u62c6\u5206\u5b57\u6bb5<br \/>\n    args[0] &#061; strtok(line_buf, &#034; &#034;);<br \/>\n    for (i &#061; 1; i &amp;lt; 5; i&#043;&#043;) {<br \/>\n        args[i] &#061; strtok(NULL, &#034; &#034;);<br \/>\n    }<\/p>\n<p>    \/\/ \u5339\u914d\u7b49\u7ea7\u5e76\u8ba1\u6570<br \/>\n    if      (0 &#061;&#061; strcmp(args[2], &#034;[DEBUG]&#034;)) count[0]&#043;&#043;;<br \/>\n    else if (0 &#061;&#061; strcmp(args[2], &#034;[INFO]&#034;))  count[1]&#043;&#043;;<br \/>\n    else if (0 &#061;&#061; strcmp(args[2], &#034;[WARN]&#034;))  count[2]&#043;&#043;;<br \/>\n    else if (0 &#061;&#061; strcmp(args[2], &#034;[ERROR]&#034;)) count[3]&#043;&#043;;<br \/>\n}<\/p>\n<p>fclose(fp);<\/p>\n<p>\/\/ \u683c\u5f0f\u5316\u8f93\u51fa<br \/>\nprintf(&#034;Debug:%d\\\\n&#034;, count[0]);<br \/>\nprintf(&#034;INFO:%d\\\\n&#034;,  count[1]);<br \/>\nprintf(&#034;WARN:%d\\\\n&#034;,  count[2]);<br \/>\nprintf(&#034;ERROR:%d\\\\n&#034;, count[3]);<br \/>\nprintf(&#034;Total:%d\\\\n&#034;, count[0] &#043; count[1] &#043; count[2] &#043; count[3]);<\/p>\n<p>return 0;<br \/>\n} <\/p>\n<h3>\u4e94\u3001\u9ad8\u9891\u8e29\u5751\u70b9\u603b\u7ed3<\/h3>\n<li>perror \u4e0d\u80fd\u4e71\u7528perror \u53ea\u80fd\u7528\u4e8e\u7cfb\u7edf\u8c03\u7528 \/ \u6807\u51c6\u5e93\u51fd\u6570\u5931\u8d25\u540e\u7684\u9519\u8bef\u6253\u5370&#xff08;\u914d\u5408 errno&#xff09;&#xff0c;\u666e\u901a\u53c2\u6570\u9519\u8bef\u5e94\u8be5\u7528 fprintf(stderr, &#8230;)&#xff0c;\u5426\u5219\u4f1a\u6253\u5370\u65e0\u610f\u4e49\u7684\u7cfb\u7edf\u9519\u8bef\u4fe1\u606f\u3002<\/li>\n<li>fgets \u81ea\u5e26\u6362\u884c\u7b26fgets \u4f1a\u628a\u884c\u5c3e\u7684 \\\\n \u4e00\u8d77\u8bfb\u8fdb\u7f13\u51b2\u533a&#xff0c;\u6253\u5370\u65f6\u4e0d\u8981\u518d\u52a0 \\\\n&#xff0c;\u5426\u5219\u4f1a\u51fa\u73b0\u53cc\u91cd\u7a7a\u884c\u3002<\/li>\n<li>strtok \u7834\u574f\u539f\u5b57\u7b26\u4e32 \u5982\u679c\u62c6\u5206\u540e\u8fd8\u9700\u8981\u4f7f\u7528\u539f\u5b57\u7b26\u4e32&#xff0c;\u4e00\u5b9a\u8981\u5148\u62f7\u8d1d\u4e00\u4efd\u526f\u672c\u518d\u62c6\u5206\u3002<\/li>\n<li>\u786c\u7f16\u7801\u8def\u5f84\u7edf\u4e00\u7528\u5b8f \u65e5\u5fd7\u6587\u4ef6\u8def\u5f84\u4e0d\u8981\u6563\u5199\u5728\u5404\u4e2a\u51fd\u6570\u91cc&#xff0c;\u5728\u5934\u6587\u4ef6\u5b9a\u4e49 #define FILENAME &#034;.\/logs\/app.log&#034;&#xff0c;\u6539\u8def\u5f84\u53ea\u9700\u8981\u6539\u4e00\u5904\u3002<\/li>\n<li>\u6b7b\u5faa\u73af\u5199\u6cd5\u7b49\u4ef7\u6027while(1) &#043; if(&#8230;) break \u548c while(\u6761\u4ef6) \u903b\u8f91\u5b8c\u5168\u7b49\u4ef7&#xff0c;\u53ea\u662f\u5199\u6cd5\u4e0d\u540c&#xff0c;\u6b7b\u5faa\u73af\u5f62\u5f0f\u66f4\u4fbf\u4e8e\u5728\u5faa\u73af\u4e2d\u95f4\u505a\u9000\u51fa\u5224\u65ad\u3002<\/li>\n<h3>\u516d\u3001\u8fd0\u884c\u6548\u679c\u6f14\u793a<\/h3>\n<p># \u5199\u5165\u51e0\u6761\u6d4b\u8bd5\u65e5\u5fd7<br \/>\n.\/minilog write INFO &#034;system start&#034;<br \/>\n.\/minilog write DEBUG &#034;init config&#034;<br \/>\n.\/minilog write ERROR &#034;disk full&#034;<br \/>\n.\/minilog write WARN &#034;memory low&#034;<br \/>\n\u67e5\u770b\u5168\u90e8\u65e5\u5fd7<br \/>\n.\/minilog list<br \/>\n\u53ea\u770bERROR\u7b49\u7ea7\u65e5\u5fd7<br \/>\n.\/minilog find ERROR<br \/>\n\u7edf\u8ba1\u5404\u7b49\u7ea7\u6570\u91cf<br \/>\n.\/minilog count <\/p>\n<h3>\u603b\u7ed3<\/h3>\n<p>\u672c\u7bc7\u6211\u4eec\u4ece\u4e3b\u51fd\u6570\u547d\u4ee4\u884c\u89e3\u6790\u5165\u624b&#xff0c;\u5bf9\u6bd4\u4e86\u7cfb\u7edf\u8c03\u7528\u4e0e\u6807\u51c6 IO \u7684\u8bfb\u53d6\u5dee\u5f02&#xff0c;\u5b8c\u6574\u5b9e\u73b0\u4e86\u65e5\u5fd7\u7684\u67e5\u770b\u3001\u7b5b\u9009\u3001\u7edf\u8ba1\u4e09\u5927\u529f\u80fd&#xff0c;\u6838\u5fc3\u6536\u83b7\u7684\u77e5\u8bc6\u70b9&#xff1a;<\/p>\n<li>\u547d\u4ee4\u884c\u53c2\u6570 argc\/argv \u7684\u4f7f\u7528\u4e0e\u4e3b\u51fd\u6570\u5206\u53d1\u8bbe\u8ba1<\/li>\n<li>fopen\/fgets\/fclose \u6807\u51c6 IO 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