19 Diagnostics library [diagnostics]

19.2 Exception classes [std.exceptions]

19.2.7 Class runtime_­error [runtime.error]

namespace std {
  class runtime_error : public exception {
    explicit runtime_error(const string& what_arg);
    explicit runtime_error(const char* what_arg);
The class runtime_­error 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_­arg.c_­str()) == 0.
runtime_error(const char* what_arg);
Postconditions: strcmp(what(), what_­arg) == 0.