Cheat Engine

oib111 · Posted: Tue Sep 25, 2007 8:45 pm Post subject: #pragma once?

In C++ I sometimes see code and they are using #pragma once, I mean what does that even do?

appalsap · Posted: Tue Sep 25, 2007 8:55 pm Post subject:

Insures the header file will only be included once (so you don't run into problems like type and function redefinitions)

assaf84 · Posted: Wed Sep 26, 2007 2:52 am Post subject:

How do you use this exactly?

atom0s · Posted: Wed Sep 26, 2007 3:53 am Post subject:

Just add #pragma once to the top of the file.

It's a newer method of doing:

TerryDonahugh · Posted: Wed Sep 26, 2007 2:47 pm Post subject:

atom0s · Posted: Wed Sep 26, 2007 6:16 pm Post subject:

I mainly code in VS which is why I mentioned it being 'newer'. As Microsoft notes too, #pragma once can greatly increase compile times, but as you already said, portability comes into play then as some compilers, like GCC, have issues with it which label it obsolete.

According to the Wiki:
LCC (2004) labeled it as having issues.
GCC (1998) labeled it as having issues, then 2005 as obsolete.

For me since I code mainly in VS2005, I just use #pragma once. Most of my old work has been closed source so I never had to worry about others having to compile my stuff so I never bothered with the other method except for older projects when I used VS6.