struct.cpp

// in C++
class Foo {
  int a;
  int b;

  void set_a(int a) {
    this->a = a;
  }
  
  void set_b(int b) { 
    this->b = b; 
  }

  void print() {
    std::cout << this->a << " " << this->b << std::endl;
  }
};

// in C

typedef struct {
  int a;
  int b;
} Foo;

void foo_set_a(Foo *this, a) {
  this->a = a;
}

void foo_set_b(Foo *this, b) {
  this->b = b;
}

void foo_print(Foo *this) {
  printf("%d %d", this->a, this->b);
}

int main(void) {

  // C++
  Foo foo;
  foo.set_a(123);
  foo.set_b(123);
  foo.print();

  // C
  Foo foo;
  foo_set_a(&foo, 123);
  foo_set_b(&foo, 123);
  foo_print(&foo)
}