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# nlohmann::basic_json::type

    constexpr value_t type() const noexcept;

Return the type of the JSON value as a value from the `value_t` enumeration.

## Return value

the type of the JSON value

Value type | return value
--- | ---
`null` | `value_t::null`
boolean | `value_t::boolean`
string | `value_t::string`
number (integer) | `value_t::number_integer`
number (unsigned integer) | `value_t::number_unsigned`
number (floating-point) | `value_t::number_float`
object | `value_t::object`
array | `value_t::array`
binary | `value_t::binary`
discarded | `value_t::discarded`

## Exception safety

No-throw guarantee: this member function never throws exceptions.

## Complexity

Constant.

## Examples

Example

The following code exemplifies `type()` for all JSON types.

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

    using json = nlohmann::json;

    int main()
    {
        // create JSON values
        json j_null;
        json j_boolean = true;
        json j_number_integer = -17;
        json j_number_unsigned = 42u;
        json j_number_float = 23.42;
        json j_object = {{"one", 1}, {"two", 2}};
        json j_array = {1, 2, 4, 8, 16};
        json j_string = "Hello, world";

        // call type()
        std::cout << std::boolalpha;
        std::cout << (j_null.type() == json::value_t::null) << '\n';
        std::cout << (j_boolean.type() == json::value_t::boolean) << '\n';
        std::cout << (j_number_integer.type() == json::value_t::number_integer) << '\n';
        std::cout << (j_number_unsigned.type() == json::value_t::number_unsigned) << '\n';
        std::cout << (j_number_float.type() == json::value_t::number_float) << '\n';
        std::cout << (j_object.type() == json::value_t::object) << '\n';
        std::cout << (j_array.type() == json::value_t::array) << '\n';
        std::cout << (j_string.type() == json::value_t::string) << '\n';
    }

Output:

    true
    true
    true
    true
    true
    true
    true
    true

## Version history

- Added in version 1.0.0.
- Added unsigned integer type in version 2.0.0.
- Added binary type in version 3.8.0.

Last update: May 1, 2022
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