Unit conversion with 3 functions

Hello I am a very new to C++. I am trying to convert a given number of meters and centimeters into feet and inches using three function. I think that I am close but since i am new I am having a hard time figuring out what i have done wrong. Thanks,

Code:

#include <iostream>
using namespace std;


double unitconversion (double lengthme, double lengthcent);
void unitoutput (double lengthme, double lengthcent);


int main ()
{
    double lengthme, lengthcent;
    char answer;
    
    do
    {
         cout<<"Enter a length in meters and centimeters to be converted:";
         cin>>lengthme>>lengthcent;
         cout<<unitoutput (lengthme, lengthcent);
         cout<<"\n Test again (y/n)";
         cin>>answer;
         cout<<endl;
         }while (answer== 'y' || answer== 'y');
         
    system ("PAUSE");
    return 0;
}


double unitconversion (double lengthme, double lengthcent)
{
       lengthme=lengthme/0.3048;
       lengthcent=lengthcent/100;
       lengthcent=lengthcent/0.3048;
       lengthcent=lengthcent*12;
       return (lengthme, lengthcent);
       }
void unitoutput (double lengthme, double lenghtcent)
{
       cout<<"The length is "<<lengthme<<" ft and "<<lengthcent<<" in.\n";
       }

Errors:
1. You haven't called the unitconversion function.
2. A function can return only one value at time, you might pass the parameters as a reference.
3. don't cout<<unitoutput(lengthme, lengthcent);
just call unitoutput(lengthme, lengthcent);

Suggestions
1. You are converting the metres to feet and centimetres to inches which is not exactly helpful. You should reconsider the unitconversion function.
2. while (answer== 'y' || answer== 'y') both 'y's are in lowercase hence redundant.

Ya I know the conversion isn't very helpful. This is for a school project and it specifically asks for this conversion. Weird I know. I made the change but it is still not compiling correctly

Code:

#include <iostream>
using namespace std;
 
 
void unitconversion (double lengthme, double lengthcent);
void unitoutput (double lengthme, double lengthcent);
 
 
int main ()
{
    double lengthme, lengthcent;
    char answer;
     
    do
    {
         cout<<"Enter a length in meters and centimeters to be converted:";
         cin>>lengthme>>lengthcent;
         unitconversion (lengthme, lengthcent);
         unitoutput (lengthme, lengthcent);
         cout<<"\n Test again (y/n)";
         cin>>answer;
         cout<<endl;
         }while (answer== 'y' || answer== 'y');
          
    system ("PAUSE");
    return 0;
}
 
 
void unitconversion (double lengthme, double lengthcent)
{
       lengthme=lengthme/0.3048;
       lengthcent=lengthcent/100;
       lengthcent=lengthcent/0.3048;
       lengthcent=lengthcent*12;
       }
void unitoutput (double lengthme, double lengthcent)
{
       cout<<"The length is "<<lengthme<<" ft and "<<lengthcent<<" in.\n";
       }

pass the parameters as a refrence.
void unitconversion (double &lengthme, double &lengthcent);
remove the return statement in unitconversion
don't cout<<unitoutput(lengthme, lengthcent);
just call unitoutput(lengthme, lengthcent)

Awesome!! Doing the '&' in front of the variables actually did the trick. Thank you for your help, I have been surprised in the subtle differences between c and c++; I really apreciate the help.