C++ File Paths Issue - c++

Question

When I use this code to load an image for SDL to render:
SDL_Texture* testimg = IMG_LoadTexture(renderer, "testz.bmp");
(or)
SDL_Texture* testimg = IMG_LoadTexture(renderer, "/testz.bmp");
the image doesn't render at all. However... if I use this code:
SDL_Texture* testimg = IMG_LoadTexture(renderer, "../bin/testz.bmp");
SDL draws the image just fine. "bin" is the folder the .exe is in. So how do I fix this file paths issue?
edit: another possibility may be that visual studio, for some reason, is running the exe it put in the bin folder in another location which doesnt have the image...

Answer 1

Because the directory where your executable is installed is not the same thing as the current directory of the process that your operating system starts, when it runs this executable.
It's fairly obvious that the current directory of your started process is the sibling directory of its executable.

Answer 2

One thing that might work is to use argv[0] to make sure the correct base path is used. Assuming you're using standard main(), it would go something like this:
std::string base_path;
int main(int argc, char* argv[]) {
base_path = argv[0];
size_t last_slash = base_path.find_last_of('/');
if(last_slash == std::string::npos)
base_path = ".";
else base_path.erase(last_slash + 1);
// Anything else you need to do in `main()`
return 0;
}
And then your loading would look like this:
SDL_Texture* testimg = IMG_LoadTexture(renderer, base_path + "testz.bmp");
If it's in a different file than main(), you'll also need to redeclare base_path with extern:
extern std::string base_path;
And of course you need to #include <string> for this to work.
If all your loading is done in main(), you can make this a bit better by moving the declaration of base_path into main():
int main(int argc, char* argv[]) {
std::string base_path = argv[0];
// The rest is the same
}