nlohmann::operator""_json_pointer

json_pointer operator ""_json_pointer(const char* s, std::size_t n);
json_pointer operator ""_json_pointer(const char8_t* s, std::size_t n);  // since C++20

This operator implements a user-defined string literal for JSON Pointers. It can be used by adding _json_pointer to a string literal and returns a json_pointer object if no parse error occurred.

It is recommended to bring the operator into scope using any of the following lines:

using nlohmann::literals::operator ""_json_pointer;
using namespace nlohmann::literals;
using namespace nlohmann::json_literals;
using namespace nlohmann::literals::json_literals;
using namespace nlohmann;

This is suggested to ease migration to the next major version release of the library. See JSON_USE_GLOBAL_UDLS for details.

Parameters

s (in) : a string representation of a JSON Pointer

n (in) : length of string s

Return value

json_pointer value parsed from s

Exceptions

The function can throw anything that json_pointer::json_pointer would throw.

Complexity

Linear.

Examples

Example

The following code shows how to create JSON Pointers from string literals.

#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>

using json = nlohmann::json;
using namespace nlohmann::literals;

int main()
{
    json j = R"( {"hello": "world", "answer": 42} )"_json;
    auto val = j["/hello"_json_pointer];

    std::cout << std::setw(2) << val << '\n';
}

Output:

"world"

Version history

Added in version 2.0.0.
Moved to namespace nlohmann::literals::json_literals in 3.11.0.
Added char8_t* overload in 3.12.x.

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