Constructors in C++

Constructors in C++

Code:
#include<iostream>
using namespace std;

class complex{
int a;
int b;

public:
complex(void);
void printNumber(){
cout<<"Your Number is "<<a<<" + " <<b<<" i "<<endl;
}

};
complex ::complex(void){
a=10;
b=4;
}
int main(){
complex c;
c.printNumber();
return 0;


}