Pragma once?
In the C and C++ programming languages, Eleven pragma is a non-standard but widely supported preprocessor directive designed to include the current source file only once per compile.
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Portability.
| Compiler | # pragma once |
|---|---|
| Intel C++ Compiler | Supported |
| Microsoft Visual C++ | Supported (since 4.2) |
Will pragma run once in GCC?
GCC officially supports #pragma once since version 3.4. GCC supports #pragma Once since version 3.4, see http://en.wikipedia.org/wiki/Pragma_once for more compiler support.
What is a C pragma for?
The #pragma preprocessor directive is used to provide additional information to the C/C++ compiler. It is used by the compiler to provide special functionality.
Is #pragma always sustainable?
The Once pragma is adopted for compatibility with other compilers and allows other forms of header-safe encoding to be used. However, Arm recommends using the #ifndef and #define encoding, as it is more portable.
Was there ever a bad pragma?
pragma has no such safety net, if the compiler mistakenly identifies a header file, the program will still not compile. If you encounter this error, your only options are to stop using #pragma once, or to rename one of the headers.
Which compilers support pragma once?
Portability
| Compiler | #pragma once |
|---|---|
| IBM XL C/C++ | Supported (since 13.1.1) |
| Intel C++ Compiler | Supported |
| Microsoft Visual C++ | Supported (since 4.2) |
| NVIDIA CUDA Compiler | Supported (depending on underlying host compiler) |
Where to put Pragma?
A single use of #pragma delegates to the compiler the task of detecting subsequent #include statements for the same file. You can do this efficiently and safely. The user has no right to make a mistake. Just put the directive in the first line of each header file.
What are pragma times?
In the C and C++ programming languages, Eleven pragma is a non-standard but widely supported preprocessor directive designed to include the current source file only once per compile.
What does pragma mean?
Pragma is short for pragmatic information. So easy. In a nutshell, pragmatic is an adjective that means prudent and practical.