I have got to use functions to do the calculations...my problem is I am trying to send solve back to the main ()...I've worked on this for all day...here is the source code:


//PROBLEM: math choice
#include <iostream.h>
#include <conio.h>
#include <iomanip.h>

void multiply();
void divided();
void adding();
void subtract();
int main(){
float a,b,solve;
char sign, answer;
do{
cout<<"Please enter your mathematical"<<endl;
cout<<"expression: ";
cin>>a;
cin>>sign;
cin>>b;
switch (sign){
case '+': { adding();
break;}
case '-': { subtract();
break;}
case '*': { multiply();
break;}
case '/': { divided();
break;}
default : {cout<<"Please choose either +,-,*, or /."<<endl;}}
if((sign=='+')||(sign=='-')||(sign=='*')||(sign=='/')){
cout<<"Your expression, "<<a<<sign<<b<<" = "<<solve<<endl;}
cout<<"Would you like to enter another expression?"<<endl;
cout<<"Enter 'y' for yes and 'n' for no. Answer: ";
cin>>answer;
}while(answer=='y');
getch();
return 0;}

//math evaluation functions
void adding(a,b,solve){
solve=a+b;}

void subtract(a,b, solve){
solve=a-b;}

void multiply(a,b,solve){
solve=a*b;}

void divided(a,b,solve){
solve=a/b;}


////// Here are my errors:
[Linker Error] Unresolved external 'adding()' referenced from D:\PROGRAM FILES\BORLAND\CBUILDER4\PROJECTS\MATHCHOICE.OBJ.
[Linker Error] Unresolved external 'subtract()' referenced from D:\PROGRAM FILES\BORLAND\CBUILDER4\PROJECTS\MATHCHOICE.OBJ.
[Linker Error] Unresolved external 'multiply()' referenced from D:\PROGRAM FILES\BORLAND\CBUILDER4\PROJECTS\MATHCHOICE.OBJ.
[Linker Error] Unresolved external 'divided()' referenced from D:\PROGRAM FILES\BORLAND\CBUILDER4\PROJECTS\MATHCHOICE.OBJ.

/////SOMEBODY PLEASE HELP ME!!!!