c++ pass dynamically allocated 2d vector to function

Question

I'm trying to pass a dynamically allocated 2d vector to a function by reference in c++.

Originally I was trying to do this with a 2d array, but I was told to try with a 2d vector instead. My code below is failing at the solve_point(boardExVector) line due to a conversion error.

#include <stdio.h>       /* printf */
#include <bits/stdc++.h> /* vector of strings */
using namespace std;

void solve_point(vector<char> *board){ 
    printf("solve_point\n");
    board[2][2] = 'c';
}

int main(){
    //dynamically allocate width and height
    int width = 7;
    int height = 9;
    //create 2d vector
    vector<vector<char>> boardExVector(width, vector<char>(height));
    boardExVector[1][2] = 'k';
    //pass to function by reference
    solve_point(boardExVector);
    //err: no suitable conversion function from "std::vector<std::vector<char, std::allocator<char>>, std::allocator<std::vector<char, std::allocator<char>>>>" to "std::vector<char, std::allocator<char>> *" exists
    printf("board[2][2] = %c\n", boardExVector[2][2]);
}

I'm just getting back into c++ so pointers and references are something I'm working on getting better at, I've looked for solutions to this online and have tried some already which usually involve changing the solve_point function header to include a * or & but I haven't gotten it to work yet. Any help is appreciated. Thanks

Answer 1

The function argument expects a pointer to a vector of char type, while the caller function is passing a vector of vector<char> type. Are you looking for the following changes in your function?

//bits/stdc++.h is not a standard library and must not be included.
#include <iostream>
#include <vector> /* vector of strings */
using namespace std;

void solve_point(vector<vector <char>> &board){
    printf("solve_point\n");
    board[2][2] = 'c';
}

int main(){
    //dynamically allocate width and height
    int width = 7;
    int height = 9;
    //create 2d vector
    vector<vector<char>> boardExVector(width, vector<char>(height));
    boardExVector[1][2] = 'k';
    //pass to function by reference
    solve_point(boardExVector);
    //err: no suitable conversion function from "std::vector<std::vector<char, std::allocator<char>>, std::allocator<std::vector<char, std::allocator<char>>>>" to "std::vector<char, std::allocator<char>> *" exists
    printf("board[2][2] = %c\n", boardExVector[2][2]);
}