Converting everything to and from wxString

This question seems common so I thought I'd write an article. Note that sometimes there may be more than one possible solutions, so don't forget to check the docs.

Note that it is recommended to use wxString as much as possible. Do no use char* or std::string unless you use a third-party library that requires you to do so.

Literals

A literal is a string written in code with "quotes around it". A literal is not a wxString, and will not be implicitly converted to one. This means that you can never pass in a raw literal into a wxWidget function or method.

MessageBox("I'm a mistake!")  // WRONG

Instead, Unicode builds (prior to wxWidgets 2.9) require you to use one of these macros to turn literals into wxString-compatible characters:

_("text that can be translated")
wxT("text that can't be translated")
_T("same as wxT")

char* c = "sometext";
wxT(c) // WRONG, not a literal

Rather than being a nuisance, the _(), wxT(), and _T() macros take care of some unicode issues and help with internationalization.

char* to wxString

char* chars = "Hello world";
wxString mystring(chars, wxConvUTF8);

wxString to char*

void my_function(const char* foo)
{
}
...
wxString mystring(wxT("HelloWorld"));
my_function( mystring.mb_str() );

mb_str() returns a temporary pointer. If you need to store it in a char* :

wxString mystring(wxT("HelloWorld"));
char cstring[1024];
strcpy(cstring, (const char*)mystring.mb_str(wxConvUTF8));

wxString to TCHAR

TCHAR tCharString[255];
wxString myString(_T("Hello World"));
const wxChar* myStringChars = myString.c_str();  
for (int i = 0; i < myString.Len(); i++) {
   tCharString[i] = myStringChars [i];
}
tCharString[myString.Len()] = _T('\0');

int to wxString

wxString mystring = wxString::Format(wxT("%i"),myint);

or

wxString mystring;
mystring << myint;

float to wxString

wxString mystring = wxString::Format(wxT("%f"), myfloat);

or

wxString mystring;
mystring << myfloat;

wxString to integer number

wxString number(wxT("145"));
long value;
if(!s.ToLong(&value)) { /* error! */ }

or

wxString str = _T("123");
int num;

num = wxAtoi(str);

wxString to floating-point number

wxString number(wxT("3.14159"));
double value;
if(!number.ToDouble(&value)){ /* error! */ }

std::string to wxString

std::string stlstring = "Hello world";
wxString mystring(stlstring.c_str(), wxConvUTF8);

wxString to std::string

wxString mystring(wxT("HelloWorld"));
std::string stlstring = std::string(mystring.mb_str());