How to pass and return a 3-Dimensional Array in C++?

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In C++ a 3-dimensional array can be implemented in two ways:

  • Using array (static)
  • Using vector (dynamic)

Passing a static 3D array in a function: Using pointers while passing the array. Converting it to the equivalent pointer type.

char ch[2][2][2];
void display(char (*ch)[2][2]) {
    . . .
}

Program to pass a static 3D array as a parameter:

C++

  

#include <bits/stdc++.h>

using namespace std;

  

void display(char (*ch)[2][2])

{

    for (int i = 0; i < 2; i++) {

        for (int j = 0; j < 2; j++) {

            for (int k = 0; k < 2; k++) {

                cout << "ch[" << i << "][" << j << "]["

                     << k << "] = " << ch[i][j][k] << endl;

            }

        }

    }

}

  

int main()

{

    char ch[2][2][2] = { { { 'a', 'b' }, { 'c', 'd' } },

                         { { 'e', 'f' }, { 'g', 'h' } } };

  

    

    display(ch);

    return 0;

}

Output

ch[0][0][0] = a
ch[0][0][1] = b
ch[0][1][0] = c
ch[0][1][1] = d
ch[1][0][0] = e
ch[1][0][1] = f
ch[1][1][0] = g
ch[1][1][1] = h

Passing 3D vector (dynamic array): When a vector is passed to a function, it can either be passed by value, where a copy of the vector is stored, or by reference, where the address of the vector is passed.

  • Pass by value: 

void function(vector <vector <vector < char >>> ch) {
    . . .
}

  • Pass by reference (Better):

void function(vector< vector < vector < char>>> &ch) {
    . . .
}

Program to pass a dynamic 3D array as a parameter:

C++

  

#include <bits/stdc++.h>

using namespace std;

  

void display(vector<vector<vector<char> > >& ch)

{

    for (int i = 0; i < 2; i++) {

        for (int j = 0; j < 2; j++) {

            for (int k = 0; k < 2; k++) {

                cout << "ch[" << i << "][" << j << "]["

                     << k << "] = " << ch[i][j][k] << endl;

            }

        }

    }

}

  

int main()

{

    vector<vector<vector<char> > > ch

        = { { { 'a', 'b' }, { 'c', 'd' } },

            { { 'e', 'f' }, { 'g', 'h' } } };

  

    

    display(ch);

    return 0;

}

Output

ch[0][0][0] = a
ch[0][0][1] = b
ch[0][1][0] = c
ch[0][1][1] = d
ch[1][0][0] = e
ch[1][0][1] = f
ch[1][1][0] = g
ch[1][1][1] = h

Returning a 3D array: A static array cannot be returned from a function in C++. So we have to pass a 3D vector from a function to get the functionality of returning a 3D array.

vector <vector< vector <char>>> fun() {
    vector <vector< vector <char>>> ch;
    . . .
    return ch;
}