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# nlohmann::basic_json::get_ptr

    template<typename PointerType>
    PointerType get_ptr() noexcept;

    template<typename PointerType>
    constexpr const PointerType get_ptr() const noexcept;

Implicit pointer access to the internally stored JSON value. No copies are made.

## Template parameters

`PointerType`
  pointer type; must be a pointer to `array_t`, `object_t`, `string_t`, `boolean_t`, `number_integer_t`, or `number_unsigned_t`, `number_float_t`, or `binary_t`. Other types will not compile.

## Return value

pointer to the internally stored JSON value if the requested pointer type fits to the JSON value; `nullptr` otherwise

## Exception safety

No-throw guarantee: this function never throws exceptions.

## Complexity

Constant.

## Notes

Undefined behavior

Writing data to the pointee of the result yields an undefined state.

## Examples

Example

The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.

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

    using json = nlohmann::json;

    int main()
    {
        // create a JSON number
        json value = 17;

        // explicitly getting pointers
        auto p1 = value.get_ptr<const json::number_integer_t*>();
        auto p2 = value.get_ptr<json::number_integer_t*>();
        auto p3 = value.get_ptr<json::number_integer_t* const>();
        auto p4 = value.get_ptr<const json::number_integer_t* const>();
        auto p5 = value.get_ptr<json::number_float_t*>();

        // print the pointees
        std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
        std::cout << std::boolalpha << (p5 == nullptr) << '\n';
    }

Output:

    17 17 17 17
    true

## Version history

- Added in version 1.0.0.
- Extended to binary types in version 3.8.0.

Last update: May 1, 2022
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