Assignment On Basic Mathematical Operations

Source Code
#include<iostream>
#include<conio.h>
#include<math.h>
#include<stdlib.h>
#include<iomanip>
char ch;
using namespace std;
void add(float x,float y)
{
float z;
z=x+y;
cout<<"Sum is: "<<z<<endl;
}
void sub(float x,float y)
{
float z;
z=x-y;
cout<<"\nDifference is:"<<z<<endl;
}
void mul(float x,float y)
{
float z;
z=x*y;
cout<<"Product is:"<<z<<endl;
}
void div(float x,float y)
{
float z;
if(y==0)
{
cout<<"Cannot be divided by 0"<<endl;
}
else
{
z=x/y;
cout<<"\nQuotient is:"<<z<<endl;
}
}
int main()
{
float a,b;
do
{

cout<<"Basic Mathematical Operations \n";
cout<<"Press 1 for addition \n";
cout<<"Press 2 for subtraction\n";
cout<<"Press 3 for multiplication\n";
cout<<"Press 4 for division\n";
cout<<"Press 5 for exit\n";
cout<<"Enter your choice:";
cin>>ch;
switch(ch)
{
case '1':
cout<<"Enter two numbers \n";
cin>> a>>b;
add(a,b);
break;
case '2':
cout<<"Enter two numbers \n";
cin>> a>>b;
sub(a,b);
break;
case '3':
cout<<"Enter two numbers \n";
cin>> a>>b;
mul(a,b);
break;
case '4':
cout<<"Enter two numbers \n";
cin>> a>>b;
div(a,b);
break;
case '5':
exit(0);
default:
cout<<"Invalid input..select a valid input" ;
system("cls");
}
}
while(ch!='0');
getch();
}
Output