遍历C中的二维数组

Question

I have a 2 dimensional array that contains string values. I am using an enum to keep track of the first index of the array when iterating. I am trying to find the enum (first dimension of an array) that a given string matches. Right now, my the way I'm iterating over the arrays and checking for values doesn't seem to seem to work 100% of the time because it will return the wrong enum. Does anyone see what I'm doing wrong, or know of a better way to get the index of the first array based on a matched string in the second?

NOTE: I am using Arduino, and am using String objects instead of char*.

    enum conditionType {
      CLEAR = 0,
      OVERCAST,
      CLOUDY,
      RAIN,
      THUNDERSTORM,
      SNOW
    };

    int conditionsIndex[6] = { 
      CLEAR, OVERCAST, CLOUDY, RAIN, THUNDERSTORM, SNOW}; 

    const char *conditions[][20] = {
      // CLEAR
      {
        "Clear"          }
      ,
      // OVERCAST
      {
        "Partly Cloudy"  }
      ,
      // CLOUDY
      { 
        "Shallow Fog",
        "Partial Fog",
        "Mostly Cloudy",
        "Fog","Overcast",
        "Scattered Clouds" }
      ,
      // RAIN
      {
        "Drizzle",
        "Rain",
        "Hail",
        "Mist",
        "Freezing Drizzle",
        "Patches of Fog",
        "Rain Mist",
        "Rain Showers",
        "Unknown Precipitation",
        "Unknown",
        "Low Drifting Widespread Dust",

        "Low Drifting Sand"          }
      ,
      // THUNDERSTORM
      {
        "Thunderstorm",
        "Thunderstorms and Rain",
        "Thunderstorms and Snow",
        "Thunderstorms and Ice Pellets",
        "Thunderstorms with Hail",
        "Thunderstorms with Small Hail",
        "Blowing Widespread Dust",
        "Blowing Sand",
        "Small Hail",
        "Squalls",
        "Funnel Cloud"          }
      ,
      // SNOW
      {
        "Volcanic Ash",
        "Widespread Dust",
        "Sand",
        "Haze",
        "Spray",
        "Dust Whirls",
        "Sandstorm",
        "Freezing Rain",
        "Freezing Fog",
        "Blowing Snow",    
        "Snow Showers",
        "Snow Blowing Snow Mist",
        "Ice Pellet Showers",
        "Hail Showers",
        "Small Hail Showers",
        "Snow",
        "Snow Grains",
        "Low Drifting Snow",
        "Ice Crystals",
        "Ice Pellets"          }
    };




      int currentCondition;
      for ( int i = 0; i < ( sizeof(conditionsIndex) / sizeof(int) ); i++ ) {
         int idx = conditionsIndex[i];
         for (int j = 0; j < ( sizeof(conditions[idx]) / sizeof(String) ); j++ ) {
         if ( forecast.equals(conditions[idx][j]) ) {
            currentCondition = idx;
           }
         }
       }

Answer 1

First of all, conditions is a 6 by 20 matrix of pointers to strings. Some of the rows, such as cloudy only has one pointer (out of the 20) assigned. So the loop needs to test for a null ptr and go to the next row.

I'm not going to write your code, but in psuedo-code it should be something like:

 memfill(conditions, 0, 6*20*sizeof(char *));
 for (i = 0 to 5)

   for (j = 0 to 20)

       if (conditions[i][j] == NULL) {break;}

       print("%s/n", conditions[i][j]);
       // test/compare strings, i is the enum value if a match
       // return i;

   end for j

end for i

Answer 2

Another issue with your code is that you are very likely to run out of ram. You might want to have a look into progmem.