[tonydav43]

Not long started c++, and I thought I had a handle on it, but I ordered this book called c++ without fear, and since I have started reading it I am becoming more and more confused. I am on the chapter using functions and the examples in the book firstly should mirror the examples on the internet, but they dont, and now unless I am reading this coded wrong, it has me confused. I will put comments in could please someone explain, as I think the code is wrong:

#include <iostream>
#include <math.h>
using namespace std;


int prime(int n);

int main()
 {

    int i; int being declared here as i

     while (1)
 {
         cout << "Enter a number (0 to exit) and press ENTER: ";
         cin >> i; User input now defined as i
       
  if (i == 0)             
             break; 
              
         if (prime(i)) 
                      
            cout << i << " is prime" << endl;
         else
            cout << i << " is not prime" << endl;
     }
     cout << endl;
     system("PAUSE");
     return 0;
}


int prime(int n)
 {
    int i; Int i now declared a 2nd time
    double sqrt_n = sqrt(static_cast<double>(n));

    for (i = 2; i <= sqrt_n); i++) Int i now defined a 2nd time as 2
 {
        if (n % i == 0)         
            return false;        
    }
  
    return true;  
}

Now as I has been declared and defined in main, how can you redeclare and define it in the function as a different variable, surely they would need to be 2 separate declarations and definitions, for example, use int n in the main, and int i in the function

Am I wrong in what I am saying? I have put my comments in green