在C ++中传递结构数组 - 在被调用函数中不存在结构元素，如何正确传递向量？

Question

I'm trying to make a game of sorts in c++ where the player has to move 3 '@' chars, or otherwise known in the game as bears.

I can't seem to access the contents of my structure that I created for various items in the program, such as bears and bombs. For example, the x coordinates and the symbol are inaccessible in the called function, so I'm assuming it is to do with my passed parameters and my vector not being initialised properly. Code is below:

const char BEAR('@');
const int  SIZEX(10);       //horizontal dimension
const int  SIZEY(6);        //vertical dimension

    struct Item {
    int x, y;
    char symbol;
};  
    vector<Item> bear(3); //there are supposed to be 3 bears

int main()
{
void initialiseGame(char g[][SIZEX], char m[][SIZEX], vector<Item>& b);

//local variable declarations 
char grid[SIZEY][SIZEX];    //grid for display
char maze[SIZEY][SIZEX];    //structure of the maze
initialiseGame(grid, maze, bear);   //initialise grid (incl. walls & bear)
//other irrelevant stuff

return 0;
}

void initialiseGame(char grid[][SIZEX], char maze[][SIZEX], vector<Item>& bear)
{ //initialise grid & place bear in middle
    void setInitialMazeStructure(char maze[][SIZEX], vector<Item>& bear);
    void setInitialDataFromMaze(char maze[][SIZEX], vector<Item>& bear);
    void updateGrid(char g[][SIZEX], const char m[][SIZEX], vector<Item>& bear);

    setInitialMazeStructure(maze, bear);        //initialise maze
    setInitialDataFromMaze(maze, bear); //initialise bear's position
    updateGrid(grid, maze, bear);       //prepare grid
}

void setInitialMazeStructure(char maze[][SIZEX], vector<Item>& bear)
{ //set the position of the walls in the maze
    //initialise maze configuration
    int initialMaze[SIZEY][SIZEX]   //local array to store the maze structure
        = { { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
            { 1, 2, 0, 0, 0, 0, 0, 0, 0, 1 },
            { 1, 2, 0, 1, 0, 0, 1, 0, 0, 1 },
            { 1, 2, 0, 1, 1, 0, 1, 0, 1, 1 },
            { 1, 1, 0, 0, 0, 1, 0, 0, 0, 1 },
            { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } };
    // with 1 for wall, 0 for tunnel, etc. 
    //copy into maze structure
    for (int row(0); row < SIZEY; ++row)    
        for (int col(0); col < SIZEX; ++col)
            switch (initialMaze[row][col])
            {
                case 0: maze[row][col] = TUNNEL; break;
                case 1: maze[row][col] = WALL; break;
                case 2: maze[row][col] = BEAR; break;
            }
}
void setInitialDataFromMaze(char maze[][SIZEX], const vector<Item>& bear) 
{ //extract bear's coordinates from initial maze info
    for (int row(0); row < SIZEY; ++row)
        for (int col(0); col < SIZEX; ++col)
            switch (maze[row][col])
            {
                case bear:
                {
                    bear.x = col;
                    bear.y = row;
                    maze[row][col] = TUNNEL;
                }
                break;
            }
}

This switch statement in setInitialiDateFromMaze() is where I'm getting the error with regards to the vector of Item, the error states that x & y as well as symbol do not exist as members of my struct Item.

for (int row(0); row < SIZEY; ++row)
    for (int col(0); col < SIZEX; ++col)
        switch (maze[row][col])
        {
            case bear:
            {
                bear.x = col;
                bear.y = row;
                maze[row][col] = TUNNEL;
            }
            break;
        }

What can I do to fix this error? Is my vector of 3 bears being passed correctly?

Answer 1

std::vector doesn't have member data x and y. The way you are using your vector is therefore wrong. You should access x and y in the following manner:

bear[i].x

Bound-checking:

bear.at(i).x

Answer 2

case bear:

bear is declared as a:

vector<Item> bear(3);

The case value, in a switch , must be a single, literal constant value. bear is a vector, and it is not clear what your intent is, but this is the reason for your compilation error. Not to mention that, subsequently bear.x and bear.y also makes no sense, since bear is a vector , and it does not have either x , or y , as a class member.