Calculatar in C++

Calculatar in C++

#include<iostream>
#include<cmath>
using namespace std;
int main ()
{
float a,b,PI;
int input;
cout<<endl;
cout<<"******************************* Calculator *************************************\n";
cout<<"================================================================================\n";
cout<<"Operations\t"<<"\tTrigonometric Functions"<<"\t\tLogarithmic Functions\n";
cout<<"================================================================================\n";
cout<<"1:  Division\t\t"<<"7:  Sin\t\t"<<"\t\t13:  Log"<<endl;
cout<<endl;
cout<<"2:  Multiplication\t"<<"8:  Cos\t\t"<<"\t\t14:  Log with base 10"<<endl;
cout<<endl;
cout<<"3:  Subtraction\t\t"<<"9:  Tan\t\t"<<endl;
cout<<endl;
cout<<"4:  Addition\t\t"<<"10: Inverse of Sin"<<endl;
cout<<endl;
cout<<"5:  Exponent\t\t"<<"11: Inverse of Cos"<<endl;
cout<<endl;
cout<<"6:  Square root\t\t"<<"12: Inverse of Tan"<<endl;
cout<<endl;
cout<<"Enter the function that you want to perform : ";
cin>>c;
cout<<endl;
PI=3.14159265;
switch(input)
{
case 1:
cout<<"Enter 1st number : ";
       cin>>first;
cout<<endl;
cout<<"Enter 2nd number : ";
cin>>second;
cout<<endl;
cout<<"Division = "<<first/second<<endl;
break;
case 2:
cout<<"Enter 1st number : ";
       cin>>first;
cout<<endl;
cout<<"Enter 2nd number : ";
cin>>second;
cout<<endl;
cout<<"Multiplication = "<<first*second<<endl;
break;
case 3:
cout<<"Enter 1st number : ";
       cin>>first;
cout<<endl;
cout<<"Enter 2nd number : ";
cin>>second;
cout<<endl;
cout<<"Subtraction = "<<first-second<<endl;
break;
case 4:
cout<<"Enter 1st number : ";
       cin>>first;
cout<<endl;
cout<<"Enter 2nd number : ";
cin>>second;
cout<<endl;
cout<<"Addition = "<<first+second<<endl;
break;
case 5:
cout<<"Enter 1st number : ";
       cin>>first;
cout<<endl;
cout<<"Enter 2nd number : ";
cin>>second;
cout<<endl;
cout<<"Exponent = "<<pow(first,second)<<endl;
break;
case 6:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Square Root = "<<sqrt(first)<<endl;
break;
case 7:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Sin = "<<sin(first)<<endl;
break;
case 8:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Cos = "<<cos(first)<<endl;
break;
case 9:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Tan = "<<tan(first)<<endl;
break;
case 10:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Inverse of Sin = "<<asin(first)*180.0/PI<<endl;
break;

case 11:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Inverse of Cos = "<<acos(first)*180.0/PI<<endl;
break;
case 12:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Inverse of tan = "<<atan(first)*180.0/PI<<endl;
break;
case 13:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Log = "<<log(first)<<endl;
break;
case 14:
cout<<"Enter the number : ";
       cin>>first;
cout<<endl;
cout<<"Log with base 10 = "<<log10(first)<<endl;
break;
default:
cout<<"Wrong Input"<<endl;
}


}