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nlohmann::byte_container_with_subtype::has_subtype

constexpr bool has_subtype() const noexcept;

Returns whether the value has a subtype.

Return value

whether the value has a subtype

Exception safety

No-throw guarantee: this function never throws exceptions.

Complexity

Constant.

Examples

Example

The example below demonstrates how has_subtype can check whether a subtype was set.

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

// define a byte container based on std::vector
using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;

int main()
{
    std::vector<std::uint8_t> bytes = {{0xca, 0xfe, 0xba, 0xbe}};

    // create container
    auto c1 = byte_container_with_subtype(bytes);

    // create container with subtype
    auto c2 = byte_container_with_subtype(bytes, 42);

    std::cout << std::boolalpha << "c1.has_subtype() = " << c1.has_subtype()
              << "\nc2.has_subtype() = " << c2.has_subtype() << std::endl;
}

Output:

c1.has_subtype() = false
c2.has_subtype() = true

Version history

Since version 3.8.0.


Last update: September 18, 2022