Please , help !!!
I don't understand clearly what the function of #pragma is .
Please give me some documents , some information or explanation .
Thanks.

Pragma is a compiler directive that's machine or operating system specific.

You can read about it here: http://msdn.microsoft.com/en-us/library/d9x1s805.aspx

Like any compiler directive, it's processed before your program is actually compiled. For instance, the #pragma once directive asks the compiler to include a header file only once, in case multiple included files contain references to the same header. This happens prior to compilation.

Pragma directives are generally specific to a machine or operating system, so I suppose they're not recommended for cross-platform development.

Hope this helps...

Beside using this directive (#pragma) , in C++ is there any other way which has the same as function of #pragma

hi i am new to wrox forums .can anyone tell me the steps to post new thread.
Thanks to you

- Sign in
- Select the book forum .
- Step 1 : click on Newthread .
- Step 2 : type your title and message .
- Step 3 : click on submit thread .
That's all .

It depends. There isn't just one #pragma command, there are several commands with the #pragma directive (follow the link I included previously). Many, if not most, are specific to the compiler, OS, or machine that they're designed for.

For the example I cited above, #pragma once, there is an ANSI equivalent listed on page 455 of the book.
For the others, I imagine there are some cross-platform compatible equivalents, but due to the nature of #pragma, it has no universal equivalent.

Dear Sally !
As you said , we can define a new header file (BOX_H) which has the same as function as #pragma , and #pragma is not universal . Is that right ?
I wanna ask is there any header file or key word or .... in C++ which can do the same work like #pragma
Thank Sally for helping !!!