Input and output

All of mp++’s multiprecision classes support stream insertion:

std::cout << int_t{42} << '\n';        // "42"
std::cout << rat_t{-6, 7} << '\n';     // "-6/7"
std::cout << real128{"1.1"} << '\n';   // "1.10000000000000000000000000000000008e+00"
std::cout << real{"1.3", 150} << '\n'; // "1.3000000000000000000000000000000000000000000006"

Starting from mp++ 0.14, integer and rational honour the format flags in output streams:

#include <iomanip>
#include <ios>

std::cout << std::hex << std::showbase << int_t{42} << '\n'; // "0x2a"
std::cout << std::oct << std::showbase << std::showpos
          << std::setw(10) << std::setfill('*')
          << int_t{42} << '\n';                              // "******+052"
std::cout << std::hex << std::showbase << std::uppercase
          << rat_t{227191947ll, 13} << '\n';                 // "0XD8AAC8B/0XD"

Starting from mp++ 0.24, the real and complex floating-point classes also honour the format flags in output streams:

#include <iomanip>
#include <ios>

std::cout << std::scientific << std::setprecision(6) << real{1 / 3.} << '\n'; // "3.333333e-01"
std::cout << std::hexfloat << std::uppercase << complex{1.1, 1.3} << '\n';    // "(0X1.199999999999AP+0,0X1.4CCCCCCCCCCCDP+0)"
std::cout << std::fixed << std::showpoint << std::showpos << 42_rq << '\n';   // "+42.000000"

Starting from mp++ 0.27, all of mp++’s multiprecision classes support formatting via the {fmt} library, provided that mp++ has been built with the MPPP_WITH_FMT option enabled (see the installation instructions):

#include <iostream>

#include <fmt/core.h>

std::cout << fmt::format("The answer is {}", int_t{42}); // "The answer is 42"

All of mp++’s multiprecision classes also provide to_string() member functions that convert the multiprecision values into string representations (see, e.g., mppp::integer::to_string(), mppp::rational::to_string(), etc.). These member functions always return a round-tripping string representation of the multiprecision value: feeding back the string representation to a constructor from string will initialise a value identical to the original one.