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C++ - Multi-dimensional Arrays



Multi-dimensional array can be viewed as arrays of arrays. C++ allows you to define multi-dimensional arrays. The following syntax can be used to create a multi-dimensional array.

Syntax

//2-dimensional array of type int 
//and size (n, m)
int MyArray [n][m];    

//3-dimensional array of type float 
//and size (p, q, r)
float MyArray [p][q][r]; 

//n-dimensional array of type double 
//and size (x1, x2,..., xn)
double MyArray [x1][x2]...[xn]; 

Two-dimensional arrays

The simplest form of the multi-dimensional array is a two-dimensional array. To declare a two-dimensional array of size (3, 4) and type int, the following syntax can be used:

//2-dimension array of type int and size (3, 4)
int A [3][4];    

This two-dimensional array can be viewed as a table containing three rows and four columns. Additionally, the element of the array can be identified as A[ i ][ j ], where A is the name of the array, and i and j are the row number and column number respectively. The figure below represents this concept:

cpp multi-dimensional array

Initialize two-dimensional arrays

A multi-dimensional array can be initialized by specifying values enclosed by brackets for each row. To initialize a two-dimensional integer array of size (3, 4) the following syntax can be used:

int A[3][4] = {  
  {0, 1, 2, 3},    //initializing row 0
  {4, 5, 6, 7},    //initializing row 1
  {8, 9, 10, 11}   //initializing row 2
};    

The nested braces, which indicate the row number are optional. The following initialization is equivalent to previous example:

int A[3][4] = {0,1,2,3,4,5,6,7,8,9,10,11}; 

Along with this, elements can be initialized individually using the subscripts, i.e, row index and column index of the array as shown below:

A[0][0] = 0; 
A[0][1] = 1; 

Access elements of a two-dimensional array

The elements of the array can be accessed using the subscripts. The example below describes how to initialize and access elements of a 2-dimensional array.

#include <iostream>
using namespace std;
 
int main (){
  int A[2][4] = {{0, 1, 2, 3}, {4, 5, 6, 7}};
  int B[2][4] = {10, 20, 30, 40, 50, 60, 70, 80};
  int C[2][4];
  
  //initializing each element of array C individually
  int k = 0;
  for(int i = 0; i < 2; i++) {
    for(int j = 0; j < 4; j++) {
      C[i][j] = k+10;
      k++;
    }
  }

  //displaying array A
  cout<<"Array A contains: \n";
  for(int i = 0; i < 2; i++) {
    for(int j = 0; j < 4; j++) {
      cout<<A[i][j]<<" ";
    }
    cout<<"\n";
  }
  
  //displaying array B
  cout<<"\nArray B contains: \n";
  for(int i = 0; i < 2; i++) {
    for(int j = 0; j < 4; j++) {
      cout<<B[i][j]<<" ";
    }
    cout<<"\n";
  }

  //displaying array C
  cout<<"\nArray C contains: \n";
  for(int i = 0; i < 2; i++) {
    for(int j = 0; j < 4; j++) {
      cout<<C[i][j]<<" ";
    }
    cout<<"\n";
  }

  return 0;
}

The output of the above code will be:

Array A contains: 
0 1 2 3 
4 5 6 7 

Array B contains: 
10 20 30 40 
50 60 70 80 

Array C contains: 
10 11 12 13 
14 15 16 17 

❮ C++ - Arrays

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