why we this . and this-> in cpp code example

Example: What is This pointer? Explain with an Example.

Every object in C++ has access to its own address through an important pointer called this pointer.
The this pointer is an implicit parameter to all member functions.
Therefore, inside a member function, this may be used to refer to the invoking object.

Example:
#include <iostream>
using namespace std;
class Demo {
private:
  int num;
  char ch;
public:
  void setMyValues(int num, char ch){
    this->num =num;
    this->ch=ch;
  }
  void displayMyValues(){
    cout<<num<<endl;
    cout<<ch;
  }
};
int main(){
  Demo obj;
  obj.setMyValues(100, 'A');
  obj.displayMyValues();
  return 0;
}