Operator Overloading for vector holding complex numbers

Question

#include<iostream>
#include<cmath>
#include<complex>
#include<vector>

using namespace std;

vector<complex<double> > Compute_wn(int n);
int main()

{
    Compute_wn(8);
    return 0;
}


vector<complex<double> > Compute_wn(int n)
{
    vector<complex<double> > V[n];
    for(int i = 0; i<n; i++)
    {
        V[i] = complex<double>(cos(2.0*M_PI*double(i)/double(n)),sin(2.0*M_PI*double(i)/double(n)));
        cout<<V[i]<<"\t";
    }
    cout<<"\n";
}

I am new to C++. When I compile this code the error I get is that error: no viable overloaded '='. (V[i] = complex<double>(cos(2.0*M_PI*double(i)/double(n)),sin(2.0*M_PI*double(i)/double(n)));) I don't understand how I need to overload the operator '=' for a vector of complex numbers of type double. As I understand that vector is a vector of complex numbers I should be able to directly assign to V[I].

alter_igel · Accepted Answer · 2018-10-22T20:45:00.610

You're mixing array and vector syntax, and here's the culprit:

vector<complex<double>> V[n];

This defines an array of size n of vector<complex<double>>. Since n is not a compile-time constant, this shouldn't be allowed, but some compilers accept it as a non-standard extension. See here for discussion.

This means that V[i] is actually a vector<complex<double>>, not a complex<double>, and that's why you can't assign a complex<double> to it.

The fix is to correctly initialize your vector:

vector<complex<double>> V;
V.resize(n);

Note: you're currently not returning anything from your function which is declared to return vector<complex<double>>, which will cause a bad case of Undefined-Behavior-related woes. Did you mean to return V;?

Operator Overloading for vector holding complex numbers

1 Answers1