Niels Lohmann
330fbead59
* Document clang-tidy exclusions and drop unneeded ones Re-enable every excluded check in a run of clang-tidy 22 over all tests and remove the seven that never fire (cert-err58-cpp, clang-analyzer-webkit.NoUncountedMemberChecker, cppcoreguidelines-virtual-class-destructor, google-readability-function-size, hicpp-function-size, hicpp-no-assembler, readability-function-size). Document the reason for every remaining exclusion at the top of the file. Exclude in advance the checks that only exist in clang-tidy 23 and are noise here (bugprone-signed-bitwise, *-explicit-constructor, readability-trailing-comma, modernize-use-string-view), plus modernize-use-integer-sign-comparison, which needs C++20 std::cmp_less and flags deliberate casts. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy findings in documentation examples and replace redundant aliases Apply clang-tidy fixes to the documentation examples: - performance-avoid-endl: std::endl -> '\n' - readability-qualified-auto: auto -> auto* / const auto* - performance-for-range-copy: copy -> const reference - google-readability-casting: C-style cast -> static_cast Replace redundant aliases (readability-redundant-qualified-alias) such as "using json = nlohmann::json;" with "using nlohmann::json;" in the documentation, README, examples, tests, and benchmarks. Aliases at class scope and aliases of other types (with_base_class_t etc.) are kept. No changes to the library or its public API. All changed examples were compiled and run; their output matches the stored .output files (except max_size and meta, which depend on the platform and compiler). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Format doc examples with the pinned astyle Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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JSON for Modern C++
JSON for Modern C++ is a header-only C++11 library that turns JSON into a first-class C++ data type, using the operator
magic of modern C++ so that creating, reading, and modifying JSON values feels as natural as it does in languages like
Python. The whole library is available as a single header, json.hpp, with no dependencies, no subproject, and no
complex build system to set up; a companion header, json_fwd.hpp, provides forward declarations to keep compile times
down, <nlohmann/json_literals.hpp> holds the user-defined string literals on their own, and
<nlohmann/json_view.hpp> adds zero-copy views and editable documents. See
header-only integration for details. It is heavily unit-tested with 100% code
coverage, checked with Valgrind and the Clang Sanitizers for memory leaks, and continuously fuzz-tested by Google
OSS-Fuzz.
Quick start
Add the single header to your project and use the library like this:
#include <iostream>
#include <nlohmann/json.hpp>
using nlohmann::json;
int main()
{
// parse a JSON string
json j = json::parse(R"({"happy": true, "pi": 3.141})");
// access and modify values
j["name"] = "Niels";
j["list"] = {1, 0, 2};
// read a value into a C++ variable and use it
double pi = j["pi"].get<double>();
std::cout << "2 * pi = " << 2 * pi << '\n';
// serialize with an indent of 4 spaces
std::cout << j.dump(4) << '\n';
}
Get the library by copying the single header json.hpp from the
releases page into a directory nlohmann on your include path, or by installing it with a package manager:
brew install nlohmann-json # Homebrew
vcpkg install nlohmann-json # vcpkg
find_package(nlohmann_json 3.12.0 REQUIRED)
target_link_libraries(myproject PRIVATE nlohmann_json::nlohmann_json)
See Integration for CMake in detail, all supported package managers (Conan, Meson, Bazel, Conda, and more), and pkg-config.
Explore the documentation
-
:octicons-rocket-24:{ .lg .middle } Features
Creating, parsing, accessing, and serializing JSON values, JSON Pointer/Patch, binary formats, zero-copy views, and more.
-
:octicons-package-24:{ .lg .middle } Integration
Add the library to your project via a single header, CMake, a package manager, or pkg-config.
-
:octicons-book-24:{ .lg .middle } API documentation
The complete reference for
basic_jsonand its member functions, types, and related classes, as well as forjson_documentandjson_view. -
:octicons-question-24:{ .lg .middle } FAQ
Answers to common questions and known surprises when using the library.
-
:octicons-tag-24:{ .lg .middle } Releases
What changed in each release, with links to the relevant documentation.
-
:octicons-people-24:{ .lg .middle } Community
The ecosystem, contribution guidelines, governance, and quality assurance around the project.
!!! info "Unreleased changes"
This documentation is built from the `develop` branch and may describe changes that are not part of a release
yet. Their version numbers are followed by an <span class="unreleased-version">unreleased</span> badge; see
[Releases](home/releases/index.md) for what shipped in each version.
The library is licensed under the MIT License. The source code, issue tracker, and discussions are on GitHub.