C++11: Random number generator in a class [duplicate]

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• Why C++11 in-class initializer cannot use parentheses? [duplicate] 2 answers

I was thinking to generate random normal with a fixed seed for reproducible research. To illustrate my question well, I made the following minimalist codes. It reports error when I put the random generator in a class. What's wrong with the first code block? How can I fix it? Many thanks for your help!

#include <iostream>
#include <random>
using namespace std;

class RandNorm{
private:
    unsigned seed = 12345;
    std::default_random_engine generator(seed);
    std::normal_distribution<> rnorm(0,1);

public:
    double getrnorm(){
    return rnorm(generator);
    }

};

int main() {
  RandNorm x;
  cout << x.getrnorm() << endl;
  return 0;
}

But it works well it I just put in in the main function as below

#include <iostream>
#include <random>
using namespace std;

int main() {

    unsigned seed = 12345;
    std::default_random_engine generator(seed);
    std::normal_distribution<> rnorm(0,1);

    for(int i=1; i<10; i++){
        cout << rnorm(generator) << endl;
    }

 return 0;
}