How to create a List (or Array) inside the another List (or Array)?

0 0 5 minutes read

A list is a collection of similar or different types of data elements.

Dynamic Language like python can store different data types in the same list, but for statically typed language like C++, a list means a collection of similar data types. Every list item can be accessed by its indices, and for most of the languages (python, java, C++, etc.) indices start from 0.

An array is the same as the list for dynamic language, but for a language like C++ where for a list dynamic memory allocation is done by the compiler, for array user has to do it manually.

Implementation of List inside List using C++:

C++

// C++ code to create a list inside another list
 
#include <bits/stdc++.h>
using namespace std;
 
int main()
{
    // Inside this list the another list
    // will be created/inserted.
    // Also ListofList only can store
    // vector<int> datatype, unlike
    // python which can store anything.
    list<list<int> > ListofList;
 
    // The list to be inserted,
    // normal integer type list.
    list<int> insertedList;
    for (int i = 1; i < 5; i++) {
        insertedList.push_back(i);
    }
 
    // Pushing insertedList inside ListofList
    ListofList.push_back(insertedList);
    ListofList.push_back(insertedList);
 
    for (auto it = ListofList.begin();
         it != ListofList.end(); it++) {
        for (int j : *it)
            cout << j << " ";
        cout << endl;
    }
    return 0;
}

Java

// Java code to create a list inside another list
import java.util.*;
 
class GFG{
 
  public static void main(String[] args)
  {
 
    // Inside this list the another list
    // will be created/inserted.
    // Also ListofList only can store
    // Vector<Integer> datatype, unlike
    // Java which can store anything.
    ArrayList<ArrayList<Integer> > ListofList = new ArrayList<ArrayList<Integer> >();
 
    // The list to be inserted,
    // normal integer type list.
    ArrayList<Integer> insertedList = new ArrayList<Integer>();
    for (int i = 1; i < 5; i++) {
      insertedList.add(i);
    }
 
    // Pushing insertedList inside ListofList
    ListofList.add(insertedList);
    ListofList.add(insertedList);
 
    for (ArrayList<Integer> it : ListofList){
      for (int j : it)
        System.out.print(j+ " ");
      System.out.println();
    }
  }
}
 
// This code is contributed by shikhasingrajput

C#

// C# code to create a list inside another list
using System;
using System.Collections.Generic;
 
public class GFG{
 
  public static void Main(String[] args)
  {
 
    // Inside this list the another list
    // will be created/inserted.
    // Also ListofList only can store
    // List<int> datatype, unlike
    // C# which can store anything.
    List<List<int> > ListofList = new List<List<int> >();
 
    // The list to be inserted,
    // normal integer type list.
    List<int> insertedList = new List<int>();
    for (int i = 1; i < 5; i++) {
      insertedList.Add(i);
    }
 
    // Pushing insertedList inside ListofList
    ListofList.Add(insertedList);
    ListofList.Add(insertedList);
 
    foreach (List<int> it in ListofList){
      foreach (int j in it)
        Console.Write(j+ " ");
      Console.WriteLine();
    }
  }
}
 
// This code is contributed by shikhasingrajput

Output

1 2 3 4 
1 2 3 4

Implementation of List inside List using Python:

For Dynamic Language like python Create 2 or more lists and append them inside one of the lists, And it’ll create a list inside a list,

Python3

list_1 = [1, 2, 3, 4]
list_2 = [4, 7, 8, 9]
list_3 = [3, 1, 4, 7]
list_4 = [3, 5, 7, 11]
 
# list_2, list_3 and list_4 
# have been appended inside list_1 
list_1.append(list_2)
list_1.append(list_3)
list_1.append(list_4)
 
# As List in python can store different data types, 
# that's why here it able to store
# integer type and List in a same list.
print(list_1)

Javascript

<script>
    // JavaScript code to create a list inside another list
    let list_1 = [1, 2, 3, 4];
    let list_2 = [4, 7, 8, 9];
    let list_3 = [3, 1, 4, 7];
    let list_4 = [3, 5, 7, 11];
 
    // list_2, list_3 and list_4
    // have been appended inside list_1
    list_1.push(list_2)
    list_1.push(list_3)
    list_1.push(list_4)
 
    // As List in python can store different data types,
    // that's why here it able to store
    // integer type and List in a same list.
    document.write(list_1)
 
    // This code is contributed by rakeshsahni
</script>

Output

[1, 2, 3, 4, [4, 7, 8, 9], [3, 1, 4, 7], [3, 5, 7, 11]]

Creating array inside the array in C:

But for statically typed language like C one have to predefine everything like the data type of the array which stores another array.

For example, to create a 1D integer array inside another array, firstly, the main array should store (int*) datatype then only, another 1D array can be stored/created inside that array.

Note: Following the same way an array can be created inside another array in C++ also.

C++

// C++ code to create array inside array
 
#include <bits/stdc++.h>
using namespace std;
#define size 5
 
int main()
{
    // Here is an array(dynamically allocated)
    // that can store array(1-D),
    // or (int*) type data
    int** out_array = (int**)malloc(size * sizeof(int*));
 
    // Here is an normal integer array
    // (dynamically allocated), which stores
    // (int) datatype
    int* temp1 = (int*)malloc(size * sizeof(int));
    int* temp2 = (int*)malloc(size * sizeof(int));
 
    for (int i = 0; i < size; i++) {
        temp1[i] = i; // 0, 1, 2, 3, 4
        temp2[i] = i;
    }
 
    // Now Creating array inside array
    // by storing int* datatype
    // inside the out_array
    out_array[0] = temp1;
    out_array[1] = temp2;
 
    cout << "After Creating array inside array " << endl;
 
    // Since there are only two
    // array inside the out_array
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < size; j++) {
            cout << out_array[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}

C

#include <stdio.h>
#include <stdlib.h>
#define size 5
 
int main()
{
    // Here is an array(dynamically allocated)
    // that can store array(1-D), or
    // (int*) type datat
    int** out_array = (int**)malloc(size * sizeof(int*));
 
    // Here is an normal integer array
    // (dynamically allocated), which
    // stores (int) datatype
    int* temp1 = (int*)malloc(size * sizeof(int));
    int* temp2 = (int*)malloc(size * sizeof(int));
 
    for (int i = 0; i < size; i++) {
        temp1[i] = i;
        temp2[i] = i;
    }
 
    // Now Creating array inside array
    // by storing int* datatype
    // inside the out_array
    out_array[0] = temp1;
    out_array[1] = temp2;
 
    printf("After Creating array inside array\n");
 
    // Since there are only two arrays
    // inside the out_array
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < size; j++) {
            printf("%d ", out_array[i][j]);
        }
        printf("\n");
    }
    return 0;
}

Java

// Java code to create array inside array
 
class GFG{
static final int size = 5;
 
public static void main(String[] args)
{
    // Here is an array(dynamically allocated)
    // that can store array(1-D),
    // or (int*) type data
    int [][]out_array = new int[size][size];
 
    // Here is an normal integer array
    // (dynamically allocated), which stores
    // (int) datatype
    int []temp1 = new int[size];
    int []temp2 = new int[size];
 
    for (int i = 0; i < size; i++) {
        temp1[i] = i; // 0, 1, 2, 3, 4
        temp2[i] = i;
    }
 
    // Now Creating array inside array
    // by storing int* datatype
    // inside the out_array
    out_array[0] = temp1;
    out_array[1] = temp2;
 
    System.out.print("After Creating array inside array " +"\n");
 
    // Since there are only two
    // array inside the out_array
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < size; j++) {
            System.out.print(out_array[i][j]+ " ");
        }
        System.out.println();
    }
}
}
 
// This code is contributed by shikhasingrajput

Output

After Creating array inside array 
0 1 2 3 4 
0 1 2 3 4

Recommended

Solve DSA problems on GfG Practice.

Solve Problems

Feeling lost in the world of random DSA topics, wasting time without progress? It’s time for a change! Join our DSA course, where we’ll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 zambiatek!