I have been getting the error sh: 1: cls: not found and dont know what to name my files extension.

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<fstream>
#include<string>
#include<ctime>
#include<conio.h>
 using namespace std;
class tt{
	public:
   	string presenttime()
      	{
   time_t now = time(0);
   char* dt = ctime(&now);
 	string d=(string)dt;
    	return d;
      	}
 };
 class form
 {
  public:
	void display(string s)
 	{
    	system("cls");
   	string line;
     	cout<<"\n"<<endl;
   	
   	fstream my(s.c_str());
 int i=0;
    	while(getline(my,line))
    	{ 
      	cout<<line<<endl;
   i++;
  if(i>=15){
  i=0;
  cin.ignore();
   }
    	}
  	my.close();
  	}
 	};
class feedback
 {
  public:
     	void feedtake(string t)
    {
   
   string s;
	ofstream my("feedback",ios::app);
       	cout<<"enter ur feedback"<<endl<<"\t";
 	cin.ignore();
        getline(cin,s);
          	tt g;   string p=g.presenttime();
              	cout<<"please enter a rating for the application[0-5] : ";
              	string x;  cin>>x;	rating(x);
		my<<endl<<"->"<<"  "<<t<<endl<<"	Rating :   "<<x<<endl<<"  "<<"  Feedback : "<<s<<endl<<"AT : "<<p<<"\n"<<endl;
              	my.close();
             	
  }
     	void maintype(string r)
    {
   
                    	
              	float y=calrating();
             	cout<<fixed<<"The average rating is : "<<y<<endl;
	cout<<"\n\n\t\t1.GIVE A FEEDBACK\n\n"<<endl;
	cout<<"\t\t2.VIEW FEEDBACK\n\n"<<endl;
     cout<<"\t\tENTER YOUR OPTION : ";
             	int x; 
  cin>>x;
            	switch(x)
               	{
   case 1:{
 	cout<<"PLEASE ENTER UR FEEDBACK"<<endl<<"->";
  	feedtake(r);
    }
    break;
   case 2: {
     form s;
  	
                  	s.display("feedback");
    }
     break;
               	}
             	
  }
	
 int fiee()
   {
	string s;
     int i=0;
	ifstream my("ratings");
 	while(getline(my,s))
      {
 
    	i++;
	  } 
 	return i;
   }
    	int calrating()
 {
   int x=fiee(); 
	int a[x];
   int  i=0;
     fstream my("ratings");
	string line;
  while(getline(my,line))
 	{
       	a[i]=stioc(line);
        	i++;
       	if(i==x)
           	break;
 	}
    	  my.close();
          	int b=0;
   	for(int i=0;i<x;i++)
      	{ 
          	b+=a[i];
    	}
         	return (b/x);
 }
	int stioc(string s)
  {
  	 int n=0;
	 for(int i=0;i<s.length();i++)
	   {
     	n+=(int)(s[i]-'0');
     	n*=10;
  	   }
   	return n/10;
 }
	void userinfo(string s)
    	{
	ofstream yy("userdetails",ios::app);
     yy<<s<<endl;
  yy.close();
 }
   	void rating(string s)
    	{ 
	ofstream xx("ratings",ios::app);
  	xx<<s<<endl;
       	xx.close();
    	}
 };
 class administrator
 {
  public:
	int admin(string b,string a)
   	{
	ifstream my(b.c_str());
  	string line;
	while(getline(my,line))
  	{
     	if(a==line)
       	return 1;
     	
   	}
    	return 0; 
 	}
 	string password()
  	{
	
  	 char ch[100],c;
   	int i=0;
 	  while((c=_getch())!=13)
  	{
	  ch[i]=c;  i++;  cout<<"*";
	  
 	} 
  	return ch;
   }
	int  maintype()
 	{
 	  cout<<"\n\n\n\n\n";
   cout<<"\t\t\tENTER  THE ROOT USER NAME : ";
      	string r;   cin>>r;
     	int c=admin("rootusers",r);
    	cout<<"\n\t\t\t"<<"   	ENTER THE PASSWORD : ";
       	string k;  k=password();
      	int f=admin("passwords",k);
    	if(c==1&&f==1)
        	{
          	system("cls");
          	cout<<"\n\n\n\n\n\n\n\t\t\t\t\t1.VIEW LAST LOGS";
    	cout<<"\n\n\n\t\t\t\t\t2.CREATE A NEW SUPER USER";
   	cout<<"\n\n\n\t\t\t\t\t\tEnter Your Option : ";
   	int m;
   	cin>>m;
    	switch(m)
     	{
     	 case 1 :{
             	form i;
                      	i.display("userdetails");   	  
    	}
     	break;
     case 2: {
     	passw:
   	system("cls");
      cout<<"\n\n\t\t\tEnter the User name : ";
   	string g,x,y;
    	cin>>g;
      	cout<<"\n\n\t\t\tEnter the Password : ";
       	x=password();
      	cout<<"\n\n\t\t\tReenter the password : ";
   	y=password();
   	int k=1;
    	if(x==y&&k!=admin("rootusers",g))
     	{
     	 rootname("rootuser",g);
     	 rootname("passwords",x);
     	 cout<<"\n\n\n\t\t\tROOT USER ADDED";
     	}
     	else
      	{
      	 cout<<"Password Don't Match || PLEASE TRY AGAIN"<<endl;
        goto passw;
       }
     }
  	break;
 	}
             	return 1;
 	}
 	else return 0;
    	
 	}
 	void rootname(string q,string s)
    	{
	ofstream yy(q.c_str(),ios::app);
     yy<<s<<endl;
    yy.close();
 }
  };
 class inter
  {
 public:
      	
     	string maintype()
     	{
     	 
     cout<<"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\t\t\t\t\t\t\t\t";
              	cout<<"ENTER YOUR NAME OR ROLL NO."<<endl;
       	  cout<<"\n\n\t\t\t\t\t\t\t\t\t1.Roll No."<<endl<<"\n\t\t\t\t\t\t\t\t\t2.Name"<<endl;
	  cout<<"\n\t\t\t\t\t\t\tChoose a option  : ";
  	   int h;   cin>>h;
   string g;
             	if(h==1)
               	{
                 	cout<<"\n\t\t\t\t\t"<<"  	"<<"Please Enter Your Roll no. : ";
                  	cin>>g;
                  	g="Roll NO. : "+g; }
              	else if(h==2)
                 	{
                 	cout<<"\n\t\t\t\t\t\t\tPlease Enter Your Name : ";
                  	cin>>g;
                 	g="Name : "+g;  }
              	tt c;  string z=c.presenttime();
          	user(g,z);
          	return g;
  }
   	
             	
     	void user(string s,string z)
   	{
    	ofstream xx("userdetails",ios::app);
    	xx<<s<<endl<<" LOGIN TIME : "<<z<<endl;
    	xx.close();
   	}
  };
int  main()
  {
	system("cls");
	inter j;
	string s=j.maintype();
	form a;  
 jump:
	system("cls");
	
	char ch='y';
 while(ch=='y'||ch=='Y')
 {
  cout<<"\n\n\n\t\t\t\t\t\t\t"<<"WELCOME TO MODERN WORLD"<<endl;
  cout<<"\n\n\n"<<endl;
  cout<<"\t\t\t\t\t1.DISLPLAY THE PERIODIC TABLE\n\n"<<endl;
  cout<<"\t\t\t\t\t2.SEARCH FOR A PERIODIC ELEMENT\n\n"<<endl;
  cout<<"\t\t\t\t\t3.HISTORY OF MODERN PERIODIC TABLE\n\n"<<endl;
  cout<<"\t\t\t\t\t4.OTHERS\n\n"<<endl;
   cout<<"\t\t\t\t\t5.EXIT\n\n"<<endl;
 	
  cout<<"\t\t\t\t ENTER YOUR CHOICE: ";
 int n;  cin>>n;
 system("cls");
  switch(n)
   {
 	case 1: a.display("structure");
         	break;
 	case 2: {
          	char key='y';
          	while(key=='y'||key=='y')
          	{ system("cls"); 
             	cout<<"\n\n\n\n\n\n\t\t\tEnter the ATOMIC No./SYMBOL/NAME of the element : ";
            	string q;  
 cin>>q;
             	ifstream xx(q.c_str());
                	if(xx)
                  	{
     a.display(q);
                           	
   }
                 	else
                   	{
	if(((int)q[0])>=65&&((int)q[0])<97)
 	{
	   q[0]=(char)(((int)q[0])+32);
 	}
	   q=(string)q;
            	a.display(q);
             	}
     cout<<"\n\n\nDo you want to continue searching[Y/y] : ";  cin>>key;
        	}
           	
         	}
        	break;
 	case 3:a.display("history");
        	break;
	case 4:
 	{
           	upp:
           		char c=_getch();
           	 system("cls");
  cout<<"\n\n\t\t\t1.ADMINISTRATOR"<<endl;
      	
  cout<<"\n\n\t\t\t2.FEEDBACK"<<endl;
  cout<<"\n\n\t\t\t3.DEVELOPER DETAILS"<<endl;
  cout<<"\n\n\t\t\t4.ABOUT"<<endl;
  cout<<"\n\n\t\t\t5.RETRUN TO MAIN MENU"<<endl;
   cout<<"\n\n\t\t\t6.EXIT\n\n"<<endl;
           	cout<<"\n\t\tEnter your choice : ";
           	int v; cin>>v;
        	system("cls");
        	switch(v)
       	{
          	case 1:
             	{
                 	administrator v;
                 	system("cls");
                 	int h=v.maintype();
  	if(h==0)
   	cout<<"\n\n\n\tENTER A VALID USERNAME OR PASSWORD";
     	char o=_getch();
            	}
             	break;
          	case 2:{
        	 feedback f;
                	f.maintype(s);
                  	char o=_getch();
                	 }
      	 break;	
    	 case 3 : {
            	system("cls");
      	a.display("details");
      	char o=_getch();   }
          	   break;
   	case 5 :{ goto jump; }
           	break;
   	case 6 :{
                     	
                     	exit(0);
                      	}
                      	break;
      	case 4 : {
                	form g; g.display("about");  
	}
              	break;
  	
     	default : cout<<"ENTER A VALID OPTION"<<endl;
    	}
      	goto upp;   	
    	}  
     	case 5 :{
              	exit(0); 
              	}
   break;  	
   default: cout<<"enter a valid option : ";
         	break;
   }
cout<<"\n\n\nDo u want to Return to main menu[Y/y] : ";
   	
 	cin>>ch;
	system("cls");
 	
  }
 return 0;
 }