C++轻量HeaderOnly的JSON库

[](https://github.com/nlohmann/json/releases) [](https://ci.appveyor.com/project/nlohmann/json) [](https://github.com/nlohmann/json/actions?query=workflow%3AUbuntu) [](https://github.com/nlohmann/json/actions?query=workflow%3AmacOS) [](https://github.com/nlohmann/json/actions?query=workflow%3AWindows) [](https://coveralls.io/github/nlohmann/json?branch=develop) [](https://scan.coverity.com/projects/nlohmann-json) [](https://app.codacy.com/gh/nlohmann/json/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade) [](https://cirrus-ci.com/github/nlohmann/json) [](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:json) [](https://wandbox.org/permlink/1mp10JbaANo6FUc7) [](https://json.nlohmann.me) [](https://raw.githubusercontent.com/nlohmann/json/master/LICENSE.MIT) [](https://github.com/nlohmann/json/releases) [](https://repology.org/project/nlohmann-json/versions) [](https://github.com/nlohmann/json/releases) [](https://github.com/nlohmann/json/issues) [](https://isitmaintained.com/project/nlohmann/json "Average time to resolve an issue") [](https://bestpractices.coreinfrastructure.org/projects/289) [](https://scorecard.dev/viewer/?uri=github.com/nlohmann/json) [](https://github.com/sponsors/nlohmann) [](https://api.reuse.software/info/github.com/nlohmann/json) [](https://discord.gg/6mrGXKvX7y) - [Design goals](#design-goals) - [Sponsors](#sponsors) - [Support](#support) ([documentation](https://json.nlohmann.me), [FAQ](https://json.nlohmann.me/home/faq/), [discussions](https://github.com/nlohmann/json/discussions), [API](https://json.nlohmann.me/api/basic_json/), [bug issues](https://github.com/nlohmann/json/issues)) - [Quick reference](#quick-reference) - [Examples](#examples) - [Read JSON from a file](#read-json-from-a-file) - [Creating `json` objects from JSON literals](#creating-json-objects-from-json-literals) - [JSON as first-class data type](#json-as-first-class-data-type) - [Serialization / Deserialization](#serialization--deserialization) - [STL-like access](#stl-like-access) - [Conversion from STL containers](#conversion-from-stl-containers) - [JSON Pointer and JSON Patch](#json-pointer-and-json-patch) - [JSON Merge Patch](#json-merge-patch) - [Implicit conversions](#implicit-conversions) - [Conversions to/from arbitrary types](#arbitrary-types-conversions) - [Specializing enum conversion](#specializing-enum-conversion) - [Binary formats (BSON, CBOR, MessagePack, UBJSON, and BJData)](#binary-formats-bson-cbor-messagepack-ubjson-and-bjdata) - [Customers](#customers) - [Supported compilers](#supported-compilers) - [Integration](#integration) - [CMake](#cmake) - [Package Managers](#package-managers) - [Pkg-config](#pkg-config) - [License](#license) - [Contact](#contact) - [Thanks](#thanks) - [Used third-party tools](#used-third-party-tools) - [Notes](#notes) - [Execute unit tests](#execute-unit-tests) ## Design goals There are myriads of [JSON](https://json.org) libraries out there, and each may even have its reason to exist. Our class had these design goals: - **Intuitive syntax**. In languages such as Python, JSON feels like a first class data type. We used all the operator magic of modern C++ to achieve the same feeling in your code. Check out the [examples below](#examples) and you'll know what I mean. - **Trivial integration**. Our whole code consists of a single header file [`json.hpp`](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json.hpp). That's it. No library, no subproject, no dependencies, no complex build system. The class is written in vanilla C++11. All in all, everything should require no adjustment of your compiler flags or project settings. The library is also included in all popular [package managers](https://json.nlohmann.me/integration/package_managers/). - **Serious testing**. Our code is heavily [unit-tested](https://github.com/nlohmann/json/tree/develop/tests/src) and covers [100%](https://coveralls.io/r/nlohmann/json) of the code, including all exceptional behavior. Furthermore, we checked with [Valgrind](https://valgrind.org) and the [Clang Sanitizers](https://clang.llvm.org/docs/index.html) that there are no memory leaks. [Google OSS-Fuzz](https://github.com/google/oss-fuzz/tree/master/projects/json) additionally runs fuzz tests against all parsers 24/7, effectively executing billions of tests so far. To maintain high quality, the project is following the [Core Infrastructure Initiative (CII) best practices](https://bestpractices.coreinfrastructure.org/projects/289). See the [quality assurance](https://json.nlohmann.me/community/quality_assurance) overview documentation. Other aspects were not so important to us: - **Memory efficiency**. Each JSON object has an overhead of one pointer (the maximal size of a union) and one enumeration element (1 byte). The default generalization uses the following C++ data types: `std::string` for strings, `int64_t`, `uint64_t` or `double` for numbers, `std::map` for objects, `std::vector` for arrays, and `bool` for Booleans. However, you can template the generalized class `basic_json` to your needs. - **Speed**. There are certainly [faster JSON libraries](https://github.com/miloyip/nativejson-benchmark#parsing-time) out there. However, if your goal is to speed up your development by adding JSON support with a single header, then this library is the way to go. If you know how to use a `std::vector` or `std::map`, you are already set. See the [contribution guidelines](https://github.com/nlohmann/json/blob/master/.github/CONTRIBUTING.md#please-dont) for more information. ## Sponsors You can sponsor this library at [GitHub Sponsors](https://github.com/sponsors/nlohmann). ### :raising_hand: Priority Sponsor - [Martti Laine](https://github.com/codeclown) - [Paul Harrington](https://github.com/phrrngtn) ### :label: Named Sponsors - [Michael Hartmann](https://github.com/reFX-Mike) - [Stefan Hagen](https://github.com/sthagen) - [Steve Sperandeo](https://github.com/homer6) - [Robert Jefe Lindstädt](https://github.com/eljefedelrodeodeljefe) - [Steve Wagner](https://github.com/ciroque) - [Lion Yang](https://github.com/LionNatsu) ### Further support