Pragma once

Preprocessor directive in C and C++

In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current header file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as include guards, but with several advantages, including less code, avoidance of name clashes, and sometimes improvement in compilation speed. While #pragma once is available in most modern compilers, its implementation is tricky and might not always be reliable.

This keyword could refer to multiple things. Here are some suggestions: