#include <iostream> 
#include <iomanip> 
#include <cmath> 

using namespace std; 

        bool isValid (int tri1, int tri2, int tri3); 
        bool side; 
          
         void calc(int a, int b, int c, double& s, double& area);
  
int main () 

{ 
        int side_a, side_b, side_c;
        double s, area;
                  
        
    // Function prompting user for 3 numbers to be used for triangle sides 
    
       while (side != 1) //Establish loop here. If side not equal to 1, error encountered, try again.
    {
       cout << "Enter 3 lengths of the triangle sides: \n"; 
       cout << " Side 1:  ";     cin >> side_a; 
       cout << " Side 2:  ";     cin >> side_b; 
       cout << " Side 3:  ";     cin >> side_c; 
       cout << endl; 
    
        
    /*Call isValid Function to determine if the user inputs are valid. 
      isValid Function needs to loop until the correct values are entered */ 
    
       bool side = isValid (side_a, side_b, side_c); 
              
      { 
        if (side = 0) 
        {
         cout << "These edges do not form a triangle."  << endl; 
         side = 0; // Populate side with 0. Error encountered. Give it another try.
        }    
        else // All ok? populate valid with 1, end the loop. 
        {
          side = 1; // If sides = triangle, end loop and continue. 
        }           
       } 
   }  // end  loop.         
          
                        
 /*Call calc Function - this function will return the value of perimeter and Area. 
 (these values were stored in the reference parameters S and Area.  Output should be perimeter  only (side a, b, c) and area.   Set precision to 4 */ 
                           
      calc (side_a, side_b, side_c, s, area); 
  
     return s * 2;   // Line 57, warning converting to int from double
      return area;  // Line 58, warning converting to int from double
             
      cout << fixed << setprecision (4);
      cout << "Your triangle has a perimeter of  " << s << " and an area of " << area << endl; 
           
 system ("pause"); 
 return 0; 
      
}//end main 
        
    // isValid Function 
        
       bool isValid (int tri1, int tri2, int tri3) 
    {   
       if ((tri1 + tri2 > tri3) && (tri1 + tri3 > tri2) && (tri2 + tri3 > tri1)) 
       side = 1; 
       else 
       side = 0; 
       return side; 
        
    } // end isValid 


     /* Write a Function 'calc'.   Return type = void, 5 parameters (a, b, c, &s, &area. 
    Calculate s = semiperimeter and area.   Results of s and area are to be stored in the 
    reference parameters s and area */ 
        
      void calc(int a, int b, int c, double& s, double& area) 
    { 
       s = ((a + b + c)/2);         
       area =(s-a)*(s-b)*(s-c); 
       area = area * s;
       area = sqrt (area);
      
      return;
         
      
    } // end calc function 

void calc(int a, int b, int c, double &s, double &area){
   s=((a+b+c)/2);
   area=sqrt (((s-a)*(s-b)*(s-c))*s);
}