how to pass a string to a c function Topic is solved

[ding]

I have try passing a wxString path to a c function locally, but it won't work. If i try passing it globally it will work. How do i pass a wxString to a c function.
At the top, that how i declare,

void extract(wxString path);

void testFrm::WxToolButton1Click(wxCommandEvent& event)
{

if (WxOpenFileDialog1->ShowModal() == wxID_OK)
{
path = WxOpenFileDialog1->GetPath();
wxMessageBox(path);
extract(path);
}

}

void extract(wxString path)
{
...
}


So any error with that?

[wxuser]

Your code seems to be ok, i dont see any problem with that.

If your issue is getting a string out of wxString, then use c_str()

Code: Select all

void extract(wxString path)
{
const char* c_string = path.c_str();
...
} 

or just pass c_string into the function

then use c_string in whatever you want it for.

[leio]

c_str() is only suitable to use for getting a wxChar out of a wxString. That means char* OR a wchar_t* based on the build type.

(const char*)mb_str(conv_class) is for always getting a char* regardless of wx build type.

(const wchar_t*)wc_str(...) is for always getting a wchar_t* out of a wxString regardless of wx build type.

extract isn't a C function if it's in the .cpp file. You are not wrapping it inside extern "C". It is taking a wxString there, and that's an instance. However, you are making a copy there, which might be unnecessary, and usually is. I suggest looking up what references are in C++.

[ding]

Thanks for helping, look like i have to pass it globally. To be exact, extract() is called a function prototype if i am not wrong. That the very basic c use to pass variable to a function but it not working at wxwidget frame.

[leio]

I don't understand what problem you are having.
The code seems generally fine. I'd certainly make the wxString argument of extract a reference, of course.
I also do not see any C involved here, other than the fact that extract is a function (that takes a C++ class instance as an argument, but that's basically like a struct), and not a static method of a class.
Can you explain what problem are you having, if any? Any compiler error, anything?

[lowjoel]

yea, you should explain what error you are getting, not expecting us to read your code and understand exactly what the error is (with no clue what we are looking for).

[ding]

Thanks for helping! I realise that I made a mistake by declaring the function prototype at the wrong place. This is how it should be place. Thanks for all your help.

..........
#include "testFrm.h"

#define filewritten "rmsd.txt"
#define filewritten1 "mean.txt"

long checkrunsample(long *,long *,wxString path);
void extract(wxString path);

//Do not add custom headers
//wxDev-C++ designer will remove them
////Header Include Start
#include "WxToolButton3_XPM.xpm"
#include "WxToolButton2_XPM.xpm"
#include "WxToolButton1_XPM.xpm"

////Header Include End

//----------------------------------------------------------------------------
// testFrm
//----------------------------------------------------------------------------
//Add Custom Events only in the appropriate block.
//Code added in other places will be removed by wxDev-C++
////Event Table Start
..............

After declaring the function below #include "testFrm.h" everything is working perfectly. Before i declare a function before #include "testFrm.h", it give a lot of error. Anyway thanks for telling me to look at the error. Probably, I was too tired at the time. Sorry.

[mathgl]

it is part of STL
i think it probably may resolve your problem