C++

Bikram Sambat dates for C++20. The core is header-only with no dependencies, the to_chars and parse paths allocate nothing, and conversion is constexpr, so it also runs at compile time. nepdate-patro is a compiled library on top of it for tithi, public holidays and events.

Install

C++ has no central registry, so pull the release tag with CMake FetchContent:

include(FetchContent)
FetchContent_Declare(nepdate
  GIT_REPOSITORY https://github.com/sanamhub/nepdate-cpp.git
  GIT_TAG v0.1.0-beta.1)
FetchContent_MakeAvailable(nepdate)
target_link_libraries(your_app PRIVATE nepdate::nepdate nepdate::patro)

Set NEPDATE_BUILD_PATRO to OFF before FetchContent_MakeAvailable if you need only the core.

Each GitHub release also has a source archive with SHA256SUMS, SHA512SUMS and a provenance attestation; its notes show the same FetchContent_Declare with the archive URL and URL_HASH. The vcpkg and Conan Center submissions are prepared but not merged upstream yet; the overlay ports in the repository work until then.

Compiler	Minimum, proved by CI
GCC	12
Clang	16, with libstdc++ and with libc++
Apple Clang	Xcode 16
MSVC	19.44 (Visual Studio 2022 17.14)

Quick start

#include <nepdate/nepdate.hpp>

#include <iomanip>
#include <iostream>

int main() {
    const nepdate::date d = nepdate::make_date(2081, 4, 15).value();
    const auto ad = d.to_year_month_day();
    std::cout << nepdate::to_string(d) << '\n';
    std::cout << static_cast<int>(ad.year()) << '-' << std::setfill('0') << std::setw(2)
              << static_cast<unsigned>(ad.month()) << '-' << std::setw(2)
              << static_cast<unsigned>(ad.day()) << '\n';
    std::cout << nepdate::to_string(nepdate::from_gregorian(ad).value()) << '\n';
}

Arithmetic and fiscal year. add_days, add_months and add_years return result<date> with overflow::clamp or overflow::spill. diff returns whole years, months and days. fiscal_year gives the start, end, range and the 2082/83 label.

Formatting. to_chars, to_chars_iso, to_chars_short, to_chars_long and to_chars_pattern write into the caller’s buffer and allocate nothing. The to_string twins return std::string. std::formatter<nepdate::date> prints {} as YYYY/MM/DD.

<chrono> interop. to_year_month_day, to_sys_days, from_gregorian, from_sys_days and from_sys_time use the standard calendar types. today(utc_offset) returns the current BS date in a fixed-offset zone, Nepal’s +05:45 by default.

Parsing

#include <nepdate/nepdate.hpp>

#include <iostream>

int main() {
    const nepdate::result<nepdate::date> strict = nepdate::parse("2081/04/15");
    const nepdate::result<nepdate::date> lenient = nepdate::parse_lenient("2081 Shrawan 15");
    std::cout << nepdate::to_string(strict.value()) << '\n';
    std::cout << nepdate::to_string(lenient.value()) << '\n';
}

Tithi, holidays and events

#include <nepdate/patro.hpp>

#include <iostream>

int main() {
    const nepdate::date d = nepdate::make_date(2081, 4, 15).value();
    const nepdate::patro::day_info day = nepdate::patro::info(d);
    if (const auto t = day.tithi()) {
        std::cout << t->name(nepdate::lang::en) << '\n';
    }
    std::cout << "holiday: " << (day.is_public_holiday() ? 1 : 0) << '\n';
    for (const nepdate::patro::event e : day.events()) {
        std::cout << e.name(nepdate::lang::en) << '\n';
    }
}

nepdate::patro::info returns an empty day_info outside BS 2077-01-01 to 2084-08-20.

Reference

Topic	Where
Every public name, with signatures	docs/API.md
Benchmarks against C# NepDate	docs/benchmarks.md
What changed	CHANGELOG.md
Source	sanamhub/nepdate-cpp