第十九天

#include<iostream>
using namespace std;
#include<cmath>
int main()
{
double x,y;
cout<<"x=";
cin>>x;
switch(int(x))
{
case 1: y=3*x-5; break;
case 2:
case 3: y=2*cos(x)+1; break;
case 4:
case 5:y=sqrt(1+x*x); break;
default: y=x*x-4*x+5;
}
cout<<"y="<<y<<endl;
}