Problems casting a const char* to char*

[ramcfloyn]

I am currently writing a C++ program that uses a external library and engine that is primarily based in C. I am attempting to load an image file and the function requires that the argument be passed as a char *szFileName.

I have the file address as a string and my attempt to convert is as follows:

std::string path("C:\\Doc.....")
then char *FileExt = path.c_str();

I continually get the error message saying that it is not possible to convert const char * to char *!

Any1 any ideas? Any help would be much appreciated!

oh and by the way ive tried casting it using static_cast

[Narue]

The c_str() method of the std::string class returns a pointer to const char so that you can't modify the result. Unfortunately, there's no good solution, and you can thank the author of the library who didn't write const-correct code. Now, if you know that the function will not modify the string, you can use const_cast to allow the conversion:

char *FileExt = const_cast<char*> ( path.c_str() );

If you're not sure whether the function will modify the string or not, you have no choice but to create a C-style string copy:

char *FileExt = new char[path.size() + 1];
std::strcpy ( FileExt, path.c_str() );

strcpy is declared in <cstring>.

>oh and by the way ive tried casting it using static_cast
static_cast doesn't remove qualifiers, which is a very good thing because you have to actively choose const_cast, and therefore can't do it by accident.

[ramcfloyn]

Thanks very much that seems do have done the trick! Won't know for sure though until i'm back in tomorrow! ;)

Cheers though It's a great help cause that was the sticking point.