Loading Different Headers Variable based

[kief12]

if i have two different headers one MyHeaderFr.h and the other MyHeaderUS.h and i have a string var that hold "US" or "FR" how do i load the header files accordingly?

Thank You,

[Nokia2280]

You have string variable with same name in both headers?If yes, the you can enclose them inside a namespace and use accordingly.

[kief12]

sorry if my original post was not clear but i want to load only one of the headers. So i load MyHeaderFR.h or MyHeaderUS.h.

[Danny]

I really have lost you completely. What exactly are you trying to do and what is the problem you're facing? Can't you simply #include the header that you need?

[kief12]

I sorry let me try to explain it better.

I have for example i have a const string in two different headers. One is US.h the other FR.h

---US.h---
const string welcome = "HI";
---FR.h---
const string welcome = "Bonjour";

i my main code i have some thing like this

string lang = "US";

depending on the value of lang i want to loader either the US.h or FR.h

[drkybelk]

just use a #define combined with #if like

#include "language_selector_header.hpp"

#if defined USE_FRENCH_HEADER
#include "FR.h"
#elif defined USE_USE_HEADER
#include "US.h"
#elif
/// ...
#endif
/// '''

and un the file language_selector_header.hpp define a variable for the language you would like to use

like

#define USE_MANDARIN_LANGUAGE

or something more clever.
Insome compilers you can even pass a preprocessor variable like that on the command line...


Cheers,

D

[nspils]

Are you looking to implement this at "run time" or at "compile time"?

[Danny]

You can't use a string object, which is a runtime notion (as are all objects) to make a decision that takes place conceptually before compilation time! When the preprocessor evaluates the #ifdef and #include expressions, the notion of strings and objects is completely inexistent yet. Think of the preprcessor as a clever text editor, not as anything that's even close to a C++ compiler.
So you need to use another macro, not a string, in order to determine during the preprocessing stage which header should be #included.
I also have to warn you that embedding string objects in a header file is a bad idea. The problem is that the header can be #included multiple times in each translation unit, and the result is multiple copies of string objects. The linker rarely has the cleverness to collapse all these strings into a single instance. A much better solution is to #define a macro in the header file and use that macro at runtime to assign a value to a shared string. Alternatively, use environment variables to determine the locale at runtime, and the load the appropriate strings from a file.

[kief12]

by doing this

 #include "language_selector_header.hpp"

#if defined USE_FRENCH_HEADER
#include "FR.h"
#elif defined USE_USE_HEADER
#include "US.h"
#elif
/// ...
#endif
/// '''

seem like i have to hard code in what language to use. I was hoping to uses a string/char variable that could be assigned after reading data from a file.

[Danny]

Then use a string table stored in a file, and load that string table into the program at runtime. You can do it more elegantly with locales, if you have some experience with this library.