Question

I wrote a numerical simulation and, as a tweak, I wanted to add some basic progress bar.
In the main loop I wrote:

if(particles.t>=pr*maxtime){
   cout << "|";
   pr+=0.01;
 }

Where pr starts at 0.01. So, basically it was supposed to cout one hundred “|” during the computation. Instead of that it couts these “|” at the end of the simulation, all at once.

And when I modify this code to:

if(particles.t>=pr*maxtime){
   cout << pr << "\n";
   pr+=0.01;
 }

it works as it should.

I guess it have something to do with optimization, I am compiling my code using g++, with options -Wall and -lm. Code like this worked when I wrote it in C#, a while ago.

Answer 1

The problem is with the buffering of the output. Place cout.flush(); after each printing and the issue should be solved.