default is a keyword used in a switch statement. If there is no case to switch on, default can be used optionally for non-case values.
#include <cassert> #include <iostream> int main() { const int dice = 1 + (std::rand() % 6); switch (dice) { case 1: std::cout << "One\n"; break; case 2: std::cout << "Two\n"; break; case 3: std::cout << "Three\n"; break; case 4: std::cout << "Four\n"; break; case 5: std::cout << "Five\n"; break; case 6: std::cout << "Six\n"; break; default: assert(!"Should not get here"); } }