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@@ -138,13 +138,74 @@ overload (3).
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associative containers such as `std::map<std::string, json>`.
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```cpp
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--8<-- "examples/get__ValueType_const.cpp"
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#include <iostream>
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#include <map>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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int main()
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{
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// create a JSON value with different types
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json json_types =
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{
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{"boolean", true},
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{
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"number", {
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{"integer", 42},
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{"floating-point", 17.23}
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}
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},
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{"string", "Hello, world!"},
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{"array", {1, 2, 3, 4, 5}},
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{"null", nullptr}
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};
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// use explicit conversions
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auto v1 = json_types["boolean"].get<bool>();
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auto v2 = json_types["number"]["integer"].get<int>();
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auto v3 = json_types["number"]["integer"].get<short>();
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auto v4 = json_types["number"]["floating-point"].get<float>();
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auto v5 = json_types["number"]["floating-point"].get<int>();
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auto v6 = json_types["string"].get<std::string>();
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auto v7 = json_types["array"].get<std::vector<short>>();
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auto v8 = json_types.get<std::map<std::string, json>>();
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// print the conversion results
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std::cout << v1 << '\n';
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std::cout << v2 << ' ' << v3 << '\n';
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std::cout << v4 << ' ' << v5 << '\n';
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std::cout << v6 << '\n';
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for (auto i : v7)
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{
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std::cout << i << ' ';
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}
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std::cout << "\n\n";
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for (auto i : v8)
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{
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std::cout << i.first << ": " << i.second << '\n';
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}
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}
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```
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Output:
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```json
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--8<-- "examples/get__ValueType_const.output"
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1
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42 42
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17.23 17
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Hello, world!
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1 2 3 4 5
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array: [1,2,3,4,5]
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boolean: true
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null: null
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number: {"floating-point":17.23,"integer":42}
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string: "Hello, world!"
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```
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??? example "Example: (2) explicit conversion to another `basic_json` specialization"
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@@ -152,13 +213,32 @@ overload (3).
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The example below shows how a `json` value is converted to an `ordered_json` value using `get<BasicJsonType>()`.
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```cpp
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--8<-- "examples/get__BasicJsonType.cpp"
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#include <iostream>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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using ordered_json = nlohmann::ordered_json;
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int main()
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{
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// create a JSON value
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json j = {{"one", 1}, {"two", 2}, {"three", 3}};
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// convert to a different basic_json specialization
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ordered_json oj = j.get<ordered_json>();
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std::cout << j << '\n';
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std::cout << oj << '\n';
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}
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```
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Output:
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```json
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--8<-- "examples/get__BasicJsonType.output"
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{"one":1,"three":3,"two":2}
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{"one":1,"three":3,"two":2}
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```
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??? example "Example: (3) explicit pointer access to the stored value"
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@@ -167,13 +247,36 @@ overload (3).
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conversions are made and a `#cpp nullptr` is returned if the value and the requested pointer type does not match.
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```cpp
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--8<-- "examples/get__PointerType.cpp"
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#include <iostream>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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int main()
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{
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// create a JSON number
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json value = 17;
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// explicitly getting pointers
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auto p1 = value.get<const json::number_integer_t*>();
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auto p2 = value.get<json::number_integer_t*>();
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auto p3 = value.get<json::number_integer_t* const>();
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auto p4 = value.get<const json::number_integer_t* const>();
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auto p5 = value.get<json::number_float_t*>();
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// print the pointees
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std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
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std::cout << std::boolalpha << (p5 == nullptr) << '\n';
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}
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```
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Output:
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```json
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--8<-- "examples/get__PointerType.output"
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17 17 17 17
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true
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```
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## See also
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