A function pointer that is a callback function to be called if an error occurs. The function will be passed an error message.

The input parameters passed to the callback function are:

  • message

A char* pointer to the error message.

The message pointer is only valid within the execution of the callback, a copy of this message string should be made and the 'message' pointer should not be used outside the scope of the callback. The char* pointer will point to undefined memory on the stack after completion of the callback function.

The 'C' code definition is:

// callback function pointer for error messages.
// the message pointer is valid only during the callback and should be copied if the message is to persist
typedef void(*errorCallbackFn)(char* message);