包含结构的向量的向量

Question

I have defined a struct

struct path{
    char type;
    bool visit;
    bool inPath;
    int level;
}

I have also defined a vector of vectors of this type struct

vector < vector<path> > spaceStation(numLevels*levelSize,vector<path> (levelSize));

I have two questions.

1) Have i defined the vector so that the number of rows pertain to (numLevels*levelSize) and columns pertain to levelSize

2) When accessing the individual elements of the vector, how can i set the elements of the struct inside it. I have tried using the .at() member function to little success

Answer 1

Re: 1

Yes. But I can't help feeling like you wanted to do this instead:

vector < vector<path> > spaceStation(numLevels,vector<path> (levelSize))

Note that using the term "rows" and "columns" is entirely in your imagination, concerning vectors. You just have a vector inside another vector. It's like an array of arrays - no special geometry implied.

Re: 2

Because you have a vector of vector, you need to use two indices, not just one:

spaceStation[level][pathindex].visit = true;

Where spaceStation[level] returns the vector at index level , which you then take the element at position pathindex (which is an instance of your struct), and finally modify a value in that struct.

Answer 2

For Q1, you are correct. For example: a 4x4 dimension vector.

vector< vector< int > > vec(4, vector(4));

For Q2, to access the path, can't you do the following:

spaceStation[2][3] to access row 2 column 3 data, for example.

Then you can do:

spaceStation[2][3].visit to access elements inside your struct.