19 Diagnostics library [diagnostics]

19.2 Exception classes [std.exceptions]

19.2.7 Class runtime_Β­error [runtime.error]

namespace std {
  class runtime_error : public exception {
  public:
    explicit runtime_error(const string& what_arg);
    explicit runtime_error(const char* what_arg);
  };
}
The class runtime_Β­error defines the type of objects thrown as exceptions to report errors presumably detectable only when the program executes.
runtime_error(const string& what_arg);
Postconditions: strcmp(what(), what_Β­arg.c_Β­str()) == 0.
runtime_error(const char* what_arg);
Postconditions: strcmp(what(), what_Β­arg) == 0.