Merging Sort in C++

merging-sort.cpp

/*
Data Structure Lab Test
Date 16/04/2011
Programmed by Tanmay Chakrabarty
CSE.

Compatible with C++, C++14, C++17
Tested at https://www.onlinegdb.com/online_c++_compiler
*/

#include <iostream>

using namespace std;

int main(){
	int first_array_size, second_array_size,i,j,k, merged_array_size;

	/*
	i will be used for the first array.
	j will be used for the second array.
	k will be used for the merged array.
	*/

	cout<<"PLEASE READ: No kind of input exceptions has been handled.\n";
	cout<<"Don't Play with Inputs.\n";
	cout<<"__________________________________________________________\n\n";

	cout<<"Please enter the number of elements of the first list : ";
	cin>>first_array_size;

	int *first_array = new int [first_array_size];

	cout<<"\nPlease enter the elements of first list in ascending order\n\n\t";
	for(i=0;i<first_array_size;i++)
	cin>>first_array[i];

	cout<<"\nPlease enter the number of elements of the second list : ";
	cin>>second_array_size;

	int *second_array = new int [second_array_size];

	cout<<"\nPlease enter the elements of second list in ascending order\n\n\t";
	for(j=0;j<second_array_size;j++)
	cin>>second_array[j];

	merged_array_size=first_array_size + second_array_size;

	int *merged_array=new int [merged_array_size];

	j=i=k=0;

	//Loop continues till we are inside of both of the arrays
	while(i<first_array_size && j<second_array_size){
		if(first_array[i] < second_array[j]){   //Finding the lowest
			merged_array[k]=first_array[i];     //Putting it in the merged array
			i++; //As value from first array has been taken, increasing i
			k++;  //increasing k for the next space of the merged array
			}
		else{
			merged_array[k]=second_array[j];
			j++;
			k++;
			}
		}

	if(i==first_array_size){ //it means, all values from first array has been taken
		for(j=j;j<second_array_size;j++){ //Thus taking rest of the values of the second array
			merged_array[k]=second_array[j];
			k++;
			}
		}
	else if(j==second_array_size){ //it means, all values from second array has been taken
		for(i=i;i<first_array_size;i++){  //Thus taking rest of the values of the first array
			merged_array[k]=first_array[i];
			k++;
			}
		}
	else{  
		//it means all the values from the two arrays has been taken and nothing to do.
		}
		
	cout<<"\n\nThe Merged array is as follows:\n\n";

	for(i=0;i<merged_array_size;i++){  //Now we can print the merged array
		if(i != (merged_array_size - 1))
			cout<<merged_array[i]<<" , ";
		else
			cout<<merged_array[i]<<"\n\n";
		}

	//system("pause");
	return 0;
	}