can i write a function in contrustor c++?

Answer 1

If I understand your question correctly, what would be preventing you from calling/invoking a function when your create a object of a class?

Something along the lines of:

#include <iostream>

void foo() {
std::cout << "I was invoked!\n";
}

class A {
public:
A()
{
foo();
}
};

int main() {
A obj;
}