Use this function to create an assertion for detailed checking.
the expression to check
This function is disabled by default. It is available for use only when the SDL_ASSERT_LEVEL is set to 3. See the Assertions Category page for details.
One can set the environment variable "SDL_ASSERT" to one of several strings ("abort", "break", "retry", "ignore", "always_ignore") to force a default behavior, which may be desirable for automation purposes. If your platform requires GUI interfaces to happen on the main thread but you're debugging an assertion in a background thread, it might be desirable to set this to "break" so that your debugger takes control as soon as assert is triggered, instead of risking a bad UI interaction (deadlock, etc) in the application.
Note that the SDL_ASSERT environment variable is an environment variable and not an SDL hint! Please refer to your platform's documentation for how to set it!