在c中拆分字符串而不使用粘着度计

Question

我想将下面的字符串(这是一个log.txt文件)裁剪到下面的子字符串中。

因为没有测定仪，所以我不能使用strtok()。

那我该怎么做呢？

日志文件的内容：

[INFO][2019-10-2323:21:45.638]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0001"}
[INFO][2019-10-2323:22:11.936]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0001"}
[INFO][2019-10-2323:22:29.232]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0002"}
[INFO][2019-10-2323:22:29.256]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0002"}
[INFO][2019-10-2323:22:33.192]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0003}
[INFO][2019-10-2323:22:48.075]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0003"}
[INFO][2019-10-2323:22:48.098]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0004"}
[INFO][2019-10-2323:22:52.034]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0004"}
[INFO][2019-10-2323:25:58.509]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0005"}
[INFO][2019-10-2323:26:42.425]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0005"}
[INFO][2019-10-2323:27:15.467]{"cmd":"set","objects":[{"type":"switch","data":["zwave-dc53:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"DC530401010001","reqid": "0006"}
[INFO][2019-10-2323:27:42.030]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-dc53:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"DC53010401000000","reqid": "0006"}
[INFO][2019-10-2323:32:45.088]{"cmd":"set","objects":[{"type":"switch","data":["zwave-ffa2:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"FFA20401010001","reqid": "0033"}
[INFO][2019-10-2323:33:11.934]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-ffa2:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"FFA2010401000000","reqid": "0007"}
[INFO][2019-10-2323:36:39.262]{"cmd":"set","objects":[{"type":"switch","data":["zwave-ffa2:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"FFA20401010001","reqid": "0008"}
[INFO][2019-10-2323:36:39.267]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-ffa2:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"FFA2010401000000","reqid": "0008"}
[INFO][2019-10-2323:36:39.267]{"cmd":"set","objects":[{"type":"switch","data":["zwave-ffa2:4-1"],"execution":{"command":"OnOff","params":{"on":true}}}],"raw":"FFA20401010001","reqid": "0022"}
[INFO][2019-10-2323:36:39.332]{"cmd":"status","objects":[{"bridge_key":"zwave","data":[{"hash":"zwave-ffa2:8-0","states":{"OnOff":{"on":false}}}],"type":"switch"}],"raw":"FFA2010401000000","reqid": "0009"}

我想要找到的子字符串是原始数据的值，例如：FFA2010401000000

Answer 1

假定原始数据是十六进制编码的(为了清晰起见，应该省略错误检查、释放内存和适当的标头)，这将有助于提取原始数据：

#define RAW_STR ",\"raw\":\""

FILE *logfile = fopen( filename, "rb" );

char *line = NULL;
size_t len = 0;

for ( ;; )
{
    ssize_t bytesRead = getline( &line, &len, logfile );
    if ( bytesRead == -1 )
    {
        break;
    }

    char *rawData = strstr( line, RAW_STR );
    if ( !raw )
    {
        continue;
    }

    // jump over the "raw":" string to the  actual value
    rawData += strlen( RAW_STR );

    // assume the data is hex
    unsigned long long value = strtoull( rawData, NULL, 16 );

    ...
}

这个简单的方法依赖于一致格式化的日志文件。如果日志文件并不总是具有精确的格式的，那么它就不能工作。

我还假设您在POSIX系统上运行，并且可以访问getline()。

Answer 2

您可能会发现正则表达式在这个场景中很有用。具体来说，雷吉塞克在这里似乎是合适的。

int regexec(const regex_t *preg, const char *string, size_t nmatch,
            regmatch_t pmatch[], int eflags);

或者是正确的json解析器。查看json格式描述网站上的C图书馆部分。