There are situations when you have one or more parameters that have values that are so frequently used that you want them to be treated as a default value for the parameter, while still having the option of allowing the caller to provide a different value if necessary. To do this, you provide the default value in the parameter list of the definition:
void log_message(const string& msg, bool clear_screen = false) { if (clear_screen) clear_the_screen(); cout << msg << endl; }
In most cases, this function is expected to be used to print a single message, but occasionally the user may want to have the screen cleared first (say, for the first message, or after a pre-determined count of lines). To accommodate this ...
