Creating an object in the loop

Question

 std::vector C(4);
 for(int i = 0; i < 1000;++i)
  for(int j = 0; j < 2000; ++j)
  {   
   C[0] = 1.0;
   C[1] = 1.0;
   C[2] = 1.0;
   C[3] = 1.         


        

Answer 1

First thing you should do is making sure that the design is OK, this means:

• Is the code easy to understand
• Does the code prevent itself against bugs
• Is the code easily extensible

I think that in this case it would indeed imply that it's better to define the variable in the loop.

Only if you have real performance problems, you may optimize your code (if the compiler didn't already do this for you), e.g. by putting the variable declaration outside the loop.