Memory leak when printing 2D array - c++

Question

I have memory leak when i print my 2D array, i looped in data from a vector into a vector called grid
Some indexes in Grid is null for example grid[8][8] is null, but grid[1][1] has a value of 3.
When i display indexes of grid with null value gives me a memory leak.
Below are my code, Any recommendations will be appreciated!
void populateAppendixB(vector<string> cityLocation, int **grid, int col, int row) {
vector<int> data = appendixB_data(cityLocation);
vector<string> appendixB_coordinates = getCoordinates(cityLocation);
vector<int> x_value = returncolValue(appendixB_coordinates);
vector<int> y_value = returnrowValue(appendixB_coordinates);
//loop data into grid[][]
for (int i = 0; i < x_value.size(); i++) {
grid[x_value[i]][y_value[i]] = data[i];
}
cout << " ";
//Top outer Grid
for (int i = 0; i < col + 2; i++) {
cout << " # ";
}
cout << " # ";
cout << endl;
//end
//y-axis
for (int j = row; j >= 0; --j) {
cout << " " << j << " # ";
for (int i = 0; i <= col; ++i) {
//displaying data
if(grid[i][j] == 0) {
cout << " ";
}
else {
cout << grid[i][j] << " ";
}
}
//Right outer Grid
cout << "#";
cout << endl;
}
//Last row of #
cout << " ";
for (int i = 0; i < col + 2; i++) {
cout << " # ";
}
cout << " # ";
cout << endl;
cout << " ";
//x-Axis
for (int i = 0; i <= col; i++) {
cout << i << " ";
}
cout << endl;
}

Answer 1

You use grid[x_value[i]][y_value[i]] = data[i];, but will not fill all of the grid since you only fill in one value of each column of grid (you only do this loop: for (int i = 0; i < x_value.size(); i++) {). Unless the grid passed in is pre-filled in with 0's properly (impossible to tell given your submitted code), then this is probably undefined behavior.
Even if it is a pre-filled in 2d array, when you print the elements of grid, you iterate from [0, cols] and [0, rows], which is likely not what you want (that iterates cols+1 columns and rows+1 rows. So, at least that last value will be accessing memory that is probably not valid.
As previous comments mention, it's a better idea to just use std::vector (e.g. std::vector<std::vector<int>> while using .at(i).at(j) to access elements which make use of C++ exceptions rather than accessing bad memory) or even std::array which are better at preventing and catching many issues cleanly. If you're worried about speed, it's probably not a huge deal and you can avoid copies by e.g. passing by reference, wrapping things in smart pointers if applicable, move semantics, etc.

Answer 2

I solved my problem by setting all my 2D array values to { }, then populate the grid array with the values that i want specifically.
It solves the memory leak problem but i am not sure if it is a good practice.