vector - String to name functions or parameters (I don't know how it is) -

i'm learning vectors , want create function called "createvector2d", have code:

    #include <iostream>     #include <vector>     #include <math.h>      using namespace std;      class vector2d {     public:         float x, y;         vector2d(float x, float y)         {             x = x;             y = y;         }          float getmagnitude()         {             return sqrt((x * x) + (y * y));         }     };      void createvector (float x, float y, string vectorname){         vector2d vectorname(x,y);         cout<<"vector created!\nname: "<<vectorname<<"\nx: "<<x<<"\ny:"<<y<<endl;     }  int main(){     float x;     float y;     string vecname;     printf ("vector velocidad (x,y)\ninserta x\n");     cin>>x;     system("cls");     printf ("vector velocidad (%f,y)\ninserta y\n", x);     cin>>y;     system("cls");     printf ("vector velocidad (%f,%f)\n", x, y);     printf ("escribe el nombre del vector\n");     cin>>vecname;     createvector (x,y,vecname);     printf ("-1. calcular magnitud (modulo)\n");     printf ("-2. enseñar vector\n");     int op = 0;     cin>>op;     switch(op){         case 1:               cout<<vecname.getmagnitude()<<endl;               break;         case 2:               cout<<"x: "<<vecname.x<<endl;                 cout<<"y: "<<vecname.y<<endl;                 break;         default:               cout<<"no elegiste nada"<<endl;               break;     }     system("pause>null");    } 

the error string can not works that, , don't know how transform works correctly vector name of class vector2d, knows? :d read.

you want have createvector() return value:

vector2d createvector(float x, float y) {     vector2d vec(x, y);     return vec; } 

the return value of function assigned vecname variable:

vector2d vecname; vecname = createvector(1, 2); 

but, don't want such function anyway, since vector2d has public constructor works fine:

vector2d vecname(1, 2);