What is difference constructor and function in programming C plus plus?

A Constructor is called when you are making a new instance of a class and member functions are functions that you can call within your class or else call using the instance of that class.

for example

class Foo {

public:

int bar;

Foo(int bar) {this->bar = bar;}

inc_bar(); {this->bar++;}

};

Foo instance(10); // Constructor is called and bar is set to 10

cout << instance.bar << endl;

instance.inc_bar(); // call the member function to increment bar

cout << instance.bar << endl;