c++ - 函数返回如何返回特定计数

Question

下面是一个计算网格中每个字符的函数。我想让这个函数返回每个字符的计数，但我被卡住了。请问如何改进下面的函数，以便我可以返回处理其他方法所需的每个计数。

int getNeighborhood(const char** grid, int N, int row, int col, int& bCount, int& fCount, int& rCount, int& gCount){
   int currRow;
   int currCol;
   int countB = 0;
   int countF = 0;
   int countR = 0;
   int countG = 0;

   //loop through all 8 grids surrounding the current row and column.
   for(int i = -1; i < 2; i++)            
   {
      for(int j = -1; j < 2; j++){
         currRow = row + i;               //current row.
         currCol = col + i;               //current column.

         if(currRow >= 0 && currRow < N && currCol >= 0 && currCol < N){
            if(grid[row][col] == 'B')
            {
               ++countB;
            }
            if(grid[row][col] == 'F')
            {
               ++countF;
            }
            if(grid[row][col] == 'R')
            {
               ++countR;
            }
            if(grid[row][col] == 'G')
            {
               ++countG;
            }
         }
      }
   //return statement required
   }

Answer 1

也许你可以使用 std::map

std::map<char,int> getNeighborhood(const char** grid, int N, int row, int col){
    int currRow;
    int currCol;
    //contain all character to count
    std::string chElementToCount = "BFGR"; 

    //The frequency is a map <char,int> correspond to <character to count, frequency>
    std::map<char, int> frequency; 

    // intialize all frequency by 0
    for (auto& ch: chElementToCount) {
        frequency.insert(std::make_pair(ch,0));
    }
    for(int i = -1; i < 2; i++)            
    {
        for(int j = -1; j < 2; j++){
            currRow = row + i;               //current row.
            currCol = col + i;               //current column.

            // just get value of current char for easier later access
            auto ch = grid[row][col];

            if(currRow >= 0 && currRow < N && currCol >= 0 && currCol < N){

                // the current char is a desired-to-count character then increase it frequency
                if (chElementToCount.find(ch) != std::string::npos)
                    frequency[ch]++;
            }
        }
    }
    return frequency;
}

这是一个使用 std::map http://www.cplusplus.com/reference/map/map/map/ 的例子