c++ - Set initial value of unknown type or overload operator for specific parameters type -

i'm still learning c++ , fiddling operator overload.

now, have produce output, while don't know kind of data type on input - it's specified in makefile , can either double, struct or enum.

code first:

#include <iostream>  #define type complex //#define type symbol //#define type double  using namespace std;  struct complex {     double re;     double im };  enum symbol {     a, b, c, d, e };  struct vector {     type data[4];     //more in struct, it's irrelevant };  // operator * overloads complex , symbol here // output stream operator vector, symbol , complex // overloaded  type operator * (vector a, vector b) {     type output;     int i;      (i=0; i<4; i++) {         output = a.data[i] * b.data[i];     }      return output;     // output garbage, because type output not     // set (to 0) @ beginning }  int main {     type x;     // ...     x = somevectora * somevectorb;     cout << x << endl;     // ...     return 0; } 

as type output value not set after initialisation, overload produce garbage @ output - helps when set it, thtere problem. setting initial values each type done in different way.

so complex it's

complex x; x.re = 0; x.im = 0; 

for symbol

symbol x; x = e; 

and double always.

the solution came overload operator specific type:

double operator * (vector a, vector b);   // [1] symbol operator * (vector a, vector b);   // [2] complex operator * (vector a, vector b);  // [3] 

but compiler throws me errors, because overloaded [3], though complex type input, , after [1] can't 2.05 * 1.1 anymore due incompatible data type.

i thinking adding init() function struct complex , struct vector. won't work enum.

checking type doesn't work either, compiler still throws errors.

the question
way set various overload procedures different input parameters or @ least avoid returning strange outputs in type operator * (vector a, vector b)?

try invoking default constructor, e.g:

type output = type();