int actions_count = 0;

enum eActionType
{
    ACTION_TYPE_NONE,
    ACTION_TYPE_ONLYCAR,
    ACTION_TYPE_ONLYPED
};

struct stActionData
{
    int key_id = 0;
    char *msg = NULL;
    int wait_time = 0;
    eActionType action_type = eActionType::ACTION_TYPE_NONE;
};

struct stActionData *action_data;
...

actions_count++;
action_data = (struct stActionData *)realloc(action_data, sizeof(struct stActionData) * actions_count);