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json/docs/mkdocs/docs/examples/operator_array__json_pointer.cpp
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Niels Lohmann 330fbead59 Document clang-tidy exclusions, drop unneeded ones, and clean up doc examples (#5909)
* 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>
2026-10-25 12:07:51 +01:00

50 lines
1.3 KiB
C++

#include <iostream>
#include <nlohmann/json.hpp>
using nlohmann::json;
using namespace nlohmann::literals;
int main()
{
// create a JSON value
json j =
{
{"number", 1}, {"string", "foo"}, {"array", {1, 2}}
};
// read-only access
// output element with JSON pointer "/number"
std::cout << j["/number"_json_pointer] << '\n';
// output element with JSON pointer "/string"
std::cout << j["/string"_json_pointer] << '\n';
// output element with JSON pointer "/array"
std::cout << j["/array"_json_pointer] << '\n';
// output element with JSON pointer "/array/1"
std::cout << j["/array/1"_json_pointer] << '\n';
// writing access
// change the string
j["/string"_json_pointer] = "bar";
// output the changed string
std::cout << j["string"] << '\n';
// "change" a nonexisting object entry
j["/boolean"_json_pointer] = true;
// output the changed object
std::cout << j << '\n';
// change an array element
j["/array/1"_json_pointer] = 21;
// "change" an array element with nonexisting index
j["/array/4"_json_pointer] = 44;
// output the changed array
std::cout << j["array"] << '\n';
// "change" the array element past the end
j["/array/-"_json_pointer] = 55;
// output the changed array
std::cout << j["array"] << '\n';
}