How to create a List (or Array) inside the another List (or Array)?
Last Updated :
23 Mar, 2024
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 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# 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
// JavaScript code to create a list inside another list
// Define ListofList using arrays (JavaScript does not have a built-in list type)
const ListofList = [];
// The list to be inserted, a normal integer type list.
const insertedList = [];
// Populate the insertedList
for (let i = 1; i < 5; i++) {
insertedList.push(i);
}
// Pushing insertedList inside ListofList
ListofList.push(insertedList.slice()); // Using slice to create a copy of the array
ListofList.push(insertedList.slice());
// Display the elements of ListofList
for (const sublist of ListofList) {
for (const element of sublist) {
console.log(element + " ");
}
console.log();
}
// This code is contributed by Yash Agarwal(yashagarwal2852002)
# Python code to create a list inside another list
# Inside this list, another list will be created/inserted.
# Also, ListofList can only store lists of integers,
# unlike Python which can store any type of object.
ListofList = []
# The list to be inserted, a normal integer type list.
insertedList = [i for i in range(1, 5)]
# Pushing insertedList inside ListofList
ListofList.append(insertedList.copy())
ListofList.append(insertedList.copy())
# Loop through ListofList and print each inner list
for innerList in ListofList:
for element in innerList:
print(element, end=" ")
print()
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,
C++
#include <iostream>
#include <vector>
int main() {
// Declare and initialize the lists
std::vector<int> list_1 = {1, 2, 3, 4};
std::vector<int> list_2 = {4, 7, 8, 9};
std::vector<int> list_3 = {3, 1, 4, 7};
std::vector<int> list_4 = {3, 5, 7, 11};
// Append elements of list_2, list_3, and list_4 to list_1
list_1.insert(list_1.end(), list_2.begin(), list_2.end());
list_1.insert(list_1.end(), list_3.begin(), list_3.end());
list_1.insert(list_1.end(), list_4.begin(), list_4.end());
// Print the combined list_1
for (const auto& elem : list_1) {
std::cout << elem << " ";
}
return 0;
}
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class Main {
public static void main(String[] args) {
// Initialize a List<Object> named list1 with initial values.
List<Object> list1 = new ArrayList<>(Arrays.asList(1, 2, 3, 4));
// Initialize three lists of integers: list2, list3, and list4.
List<Integer> list2 = new ArrayList<>(Arrays.asList(4, 7, 8, 9));
List<Integer> list3 = new ArrayList<>(Arrays.asList(3, 1, 4, 7));
List<Integer> list4 = new ArrayList<>(Arrays.asList(3, 5, 7, 11));
// Add the integer lists (list2, list3, list4) to the main list (list1).
list1.add(list2);
list1.add(list3);
list1.add(list4);
// Output the main list in a readable format.
System.out.print("[");
for (int i = 0; i < list1.size(); i++) {
Object item = list1.get(i);
if (item instanceof List) {
// If the item is a List<Integer>, format it as "[item1, item2, ...]".
List<Integer> sublist = (List<Integer>) item;
System.out.print("[" + String.join(", ", sublist.stream().map(Object::toString).toArray(String[]::new)) + "]");
} else {
System.out.print(item);
}
// Add a comma and space if the current item is not the last one.
if (i != list1.size() - 1) {
System.out.print(", ");
}
}
System.out.println("]");
}
}
using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
static void Main()
{
// Initialize a List<object> named list1 with initial values.
List<object> list1 = new List<object> { 1, 2, 3, 4 };
// Initialize three lists of integers: list2, list3, and list4.
List<int> list2 = new List<int> { 4, 7, 8, 9 };
List<int> list3 = new List<int> { 3, 1, 4, 7 };
List<int> list4 = new List<int> { 3, 5, 7, 11 };
// Add the integer lists (list2, list3, list4) to the main list (list1).
list1.Add(list2);
list1.Add(list3);
list1.Add(list4);
// Output the main list in a readable format.
Console.Write("[");
foreach (var item in list1){
if (item is List<int>){
// If the item is a List<int>, format it as "[item1, item2, ...]".
List<int> sublist = item as List<int>;
Console.Write("[" + string.Join(", ", sublist) + "]");
}
else Console.Write(item + "");
// Add a comma and space if the current item is not the last one.
if (item != list1.Last()) Console.Write(", ");
}
Console.Write("]\n");
}
}
<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>
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)
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;
}
#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 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
# Define the size of the array
size = 5
# Create a list to store arrays (2D array)
out_array = []
# Create two separate arrays (1D arrays)
temp1 = range(size)
temp2 = range(size)
# Append the arrays to the list to create a 2D array
out_array.append(temp1)
out_array.append(temp2)
print "After Creating array inside array"
# Iterate through the 2D array and print its elements
for i in range(len(out_array)):
for j in range(size):
print out_array[i][j],
print
using System;
class Program {
static void Main(string[] args)
{
const int size = 5;
// Here is an array(dynamically allocated)
// that can store array(1-D),
// or (int[]) type data
int[][] outArray = new int[size][];
// Here is a 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 outArray
outArray[0] = temp1;
outArray[1] = temp2;
Console.WriteLine(
"After Creating array inside array:");
// Since there are only two
// arrays inside the outArray
for (int i = 0; i < 2; i++) {
for (int j = 0; j < size; j++) {
Console.Write(outArray[i][j] + " ");
}
Console.WriteLine();
}
}
}
// Size of the array
const size = 5;
// Here is an array (dynamically allocated)
// that can store arrays (1-D),
// or (int[]) type data
const out_array = new Array(size);
// Here are normal integer arrays
// (dynamically allocated), which store
// (number) datatype
const temp1 = new Array(size);
const temp2 = new Array(size);
for (let i = 0; i < size; i++) {
temp1[i] = i; // 0, 1, 2, 3, 4
temp2[i] = i;
}
// Now creating array inside array
// by storing arrays (int[]) datatype
// inside the out_array
out_array[0] = temp1;
out_array[1] = temp2;
console.log("After creating array inside array: ");
// Since there are only two
// arrays inside the out_array
for (let i = 0; i < 2; i++) {
let output = "";
for (let j = 0; j < size; j++) {
output += out_array[i][j] + " ";
}
console.log(output);
}
OutputAfter Creating array inside array
0 1 2 3 4
0 1 2 3 4
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