20 General utilities library [utilities]

20.20 Formatting [format]

20.20.6 Class format_­error [format.error]

namespace std {
  class format_error : public runtime_error {
  public:
    explicit format_error(const string& what_arg);
    explicit format_error(const char* what_arg);
  };
}
The class format_­error defines the type of objects thrown as exceptions to report errors from the formatting library.
format_error(const string& what_arg);
Postconditions: strcmp(what(), what_­arg.c_­str()) == 0.
format_error(const char* what_arg);
Postconditions: strcmp(what(), what_­arg) == 0.