如何从C中的sting中提取特定字符（http响应）

1 回答

• 1

  在你开始一遍又一遍地问同一个问题之前，这是一个解决方案：

  #include <stdlib.h>
  #include <stdio.h>
  #include <string.h>
  
  /*
   *      Extracts the fist JSON object between balanced curly braces
   *      and copies it to the given buffer. Returns the length of the
   *      extracted string. At most nbuf -1 characters will be copied 
   *      and the result is always null-terminated. A return value
   *      of nbuf or higher indicates that the output aws truncated.
   *      If no object is found, -1 is returned.
   */
  int get_json(char buf[], size_t nbuf, const char *str)
  {
      const char *p, *q;
      int braces = 0;
  
      p = strchr(str, '{');
      if (p == NULL) return -1;
  
      for (q = p; *q; q++) {
          if (*q == '{') braces++;
          if (*q == '}') {
              braces--;
  
              if (braces == 0) {
                  int len = q - p + 1;
  
                  return snprintf(buf, nbuf, "%.*s", len, p);
              }
          }
      }
  
      return -1;      // brace mismatch;
  }
  
  int main()
  {
      char *str = "GET /axis-cgi/dynamicoverlay.cgi?action=settext&"
          "text=HTTP/1.1 200 OK#015#012Server: nginx#015#01"
          "2Date: Fri, 18 Sep 2015 09:39:01 GMT#015#012Cont"
          "ent-Type: application/json; charset=utf-8#015#01"
          "2Transfer-Encoding: chunked#015#012Connection: k"
          "eep-alive#015#012X-Source: redis#015#012Access-C"
          "ontrol-Allow-Origin: *#015#012Access-Control-All"
          "ow-Credentials: true#015#012Access-Control-Allow"
          "-Methods: GET, POST#015#012#015#0121c1#015#012{\""
          "coord\":{\"lon\":145.77,\"lat\":-16.92},\"weather\":[{\""
          "id\":800,\"main\":\"Clear\",\"description\":\"Sky is Cle"
          "ar\",\"icon\":\"01n\"}],\"base\":\"stations\",\"main\":{\"te"
          "mp\":296.49,\"pressure\":1013,\"humidity\":50,\"temp_m"
          "in\":295.93,\"temp_max\":297.15},\"visibility\":10000"
          ",\"wind\":{\"speed\":2.1,\"deg\":100},\"clouds\":{\"all\":"
          "0},\"dt\":1442566613,\"sys\":{\"type\":1,\"id\":8166,\"me"
          "ssage\":0.0075,\"country\":\"AU\",\"sunrise\":144252061"
          "4,\"sunset\":1442563944},\"id\":2172797,\"name\":\"Cair"
          "ns\",\"cod\":200}#012#015#0120#015#012#015#012 HTTP"
          "/1.0#015#012Authorization: Basic cm9vdDpzdHJlYW0"
          "=#015#012Host: 192.168.2.3";
      char buf[512];
      int n;
  
      n = get_json(buf, sizeof(buf), str);
      if (n >= 0) puts(buf);
  
      return 0;
  }
  

  回复于 2024-05-03T15:05:42+08:00