# <small>nlohmann::basic_json_view::</small>is_binary

```cpp
bool is_binary() const noexcept;
```

This function always returns `#!cpp false`: a document is only ever parsed from JSON text, never from CBOR or the other
binary formats, and a JSON text has no binary values, so a view can never refer to one. The function exists for
interface parity with [`BasicJsonType::is_binary`](../basic_json/is_binary.md).

## Return value

`#!cpp false`, always.

## Exception safety

No-throw guarantee: this function never throws exceptions.

## Complexity

Constant.

## Examples

??? example

    The example below classifies several parsed documents by the type of their root value, without materializing any
    of them into a `BasicJsonType` value.

    ```cpp
    #include <iostream>
    #include <nlohmann/json_view.hpp>
    
    using json_document = nlohmann::json_document;
    
    int main()
    {
        std::cout << std::boolalpha;
    
        // several incoming messages, one json_document per message. type() and
        // is_*() only look at the flat index built by parse(); no nlohmann::json
        // tree exists yet, and none is built unless materialize() is called
        json_document d_null = json_document::parse("null");
        json_document d_bool = json_document::parse("true");
        json_document d_int = json_document::parse("-42");
        json_document d_unsigned = json_document::parse("42");
        json_document d_float = json_document::parse("4.2");
        json_document d_string = json_document::parse(R"("hi")");
        json_document d_array = json_document::parse("[1, 2, 3]");
        json_document d_object = json_document::parse(R"({"a": 1})");
    
        std::cout << d_null.root().is_null() << '\n';
        std::cout << d_bool.root().is_boolean() << '\n';
        std::cout << d_int.root().is_number() << ' ' << d_int.root().is_number_integer() << '\n';
        std::cout << d_unsigned.root().is_number_unsigned() << '\n';
        std::cout << d_float.root().is_number_float() << '\n';
        std::cout << d_string.root().is_string() << '\n';
        std::cout << d_array.root().is_array() << ' ' << d_array.root().is_structured() << '\n';
        std::cout << d_object.root().is_object() << ' ' << d_object.root().is_primitive() << '\n';
    
        // JSON text can never produce a binary value: is_binary() is always false
        std::cout << d_array.root().is_binary() << '\n';
    
        // a default-constructed view, and the root of a document that failed to
        // parse without exceptions, are both discarded
        nlohmann::json_view invalid;
        json_document failed = json_document::parse("not json", /* allow_exceptions */ false);
        std::cout << invalid.is_discarded() << '\n';
        std::cout << failed.root().is_discarded() << '\n';
    
        // type() returns the same value_t enumeration as basic_json::type()
        std::cout << (d_object.root().type() == nlohmann::json::value_t::object) << '\n';
    }
    
    ```

    Output:

    ```json
    true
    true
    true true
    true
    true
    true
    true true
    true false
    false
    true
    true
    true
    
    ```

## See also

- [type](type.md) - return the type of the value
- [`BasicJsonType::is_binary`](../basic_json/is_binary.md) - the corresponding function of `basic_json`

## Version history

- Added in version 3.13.0.