Question

I have a question about my C++ homework. I am just confused about *this.

The code below is what I have.

My question is why the condition in the if statement in the = operator is true?

#include <cstring>
class abc {
      char p[9];
      int inc;
   public:
      abc( ) { inc = 8; strcpy(p, "10010101"); }
      ~abc( );
      abc& operator=(const abc &);

};

abc::~abc( ) {

}
abc& abc::operator=(const abc &c) {
   if(this != &c) { //my question is why this condition is true?
      inc = c.inc - 2;
      for(int i=0; i<inc; i++) {
     p[i] = c.p[i] + 2;
      }
   }
   return *this;
}

int main( ) {
   abc x, y;
   x = y;
   return 0;

}

Answer 1

because you don’t want to make a copy if you are assigning to yourself, that is the reason for the if condition, *this returns self instance. It is true because you are trying to assign y to x and as they are both different instances you then make a copy of y to x.