deploy: 56ddcb65f0

2026-10-03 05:00:30 +00:00 · 2026-09-27 21:37:45 +00:00
parent 0cd46537bb
commit be6bcd470b
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+# nlohmann::basic_json::to_bon8
+
+```
+// (1)
+static std::vector<std::uint8_t> to_bon8(const basic_json& j);
+
+// (2)
+static void to_bon8(const basic_json& j, detail::output_adapter<std::uint8_t> o);
+static void to_bon8(const basic_json& j, detail::output_adapter<char> o);
+```
+
+Serializes a given JSON value `j` to a byte vector using the BON8 (Binary Object Notation 8) serialization format. BON8 is a compact binary serialization format that stores strings as UTF-8 without a length prefix.
+
+1. Returns a byte vector containing the BON8 serialization.
+1. Writes the BON8 serialization to an output adapter.
+
+The exact mapping and its limitations are described on a [dedicated page](https://json.nlohmann.me/features/binary_formats/bon8/index.md).
+
+## Parameters
+
+`j` (in) : JSON value to serialize
+
+`o` (in) : output adapter to write serialization to
+
+## Return value
+
+1. BON8 serialization as a byte vector
+1. (none)
+
+## Exception safety
+
+Strong guarantee: if an exception is thrown, there are no changes in the JSON value `j`, which is never modified. With (2), the bytes written before the exception remain in the output adapter.
+
+## Exceptions
+
+- Throws [out_of_range.407](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range407) if `j` contains an unsigned integer above 9223372036854775807, which BON8 cannot represent
+- Throws [type_error.316](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error316) if `j` contains a string that is not valid UTF-8
+
+## Complexity
+
+Linear in the size of the JSON value `j`.
+
+## Examples
+
+Example
+
+The example shows the serialization of a JSON value to a byte vector in BON8 format.
+
+```
+#include <iostream>
+#include <iomanip>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+using namespace nlohmann::literals;
+
+int main()
+{
+    // create a JSON value
+    json j = R"({"compact": true, "format": "BON8", "schema": 0})"_json;
+
+    // serialize it to BON8
+    std::vector<std::uint8_t> v = json::to_bon8(j);
+
+    // print the vector content
+    for (auto& byte : v)
+    {
+        std::cout << "0x" << std::hex << std::setw(2) << std::setfill('0') << (int)byte << " ";
+    }
+    std::cout << std::endl;
+}
+```
+
+Output:
+
+```
+0x89 0x63 0x6f 0x6d 0x70 0x61 0x63 0x74 0xf9 0x66 0x6f 0x72 0x6d 0x61 0x74 0xff 0x42 0x4f 0x4e 0x38 0xff 0x73 0x63 0x68 0x65 0x6d 0x61 0x90
+```
+
+## See also
+
+- [from_bon8](https://json.nlohmann.me/api/basic_json/from_bon8/index.md) create a JSON value from an input in BON8 format
+- [to_cbor](https://json.nlohmann.me/api/basic_json/to_cbor/index.md) create a CBOR serialization of a JSON value
+- [to_msgpack](https://json.nlohmann.me/api/basic_json/to_msgpack/index.md) create a MessagePack serialization of a JSON value
+- [to_bson](https://json.nlohmann.me/api/basic_json/to_bson/index.md) create a BSON serialization of a JSON value
+- [to_ubjson](https://json.nlohmann.me/api/basic_json/to_ubjson/index.md) create a UBJSON serialization of a JSON value
+- [to_bjdata](https://json.nlohmann.me/api/basic_json/to_bjdata/index.md) create a BJData serialization of a JSON value
+
+## Version history
+
+- Added in version 3.13.0.