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### jsoncons::msgpack::encode_msgpack
Encodes a C++ data structure into the [MessagePack](http://msgpack.org/index.html) data format.
```cpp
#include <jsoncons_ext/msgpack/msgpack.hpp>
template <typename T,typename ByteContainer>
void encode_msgpack(const T& jval, ByteContainer& cont,
const msgpack_decode_options& options = msgpack_decode_options()); (1)
template <typename T>
void encode_msgpack(const T& jval, std::ostream& os,
const msgpack_decode_options& options = msgpack_decode_options()); (2)
template <typename T,typename ByteContainer>
void encode_msgpack(const allocator_set<Allocator,TempAllocator>& alloc_set,
const T& jval, ByteContainer& cont,
const msgpack_decode_options& options = msgpack_decode_options()); (3) (since 0.171.0)
template <typename T>
void encode_msgpack(const allocator_set<Allocator,TempAllocator>& alloc_set,
const T& jval, std::ostream& os,
const msgpack_decode_options& options = msgpack_decode_options()); (4) (since 0.171.0)
```
(1) Writes a value of type T into a byte container in the MessagePack data format, using the specified (or defaulted) [options](msgpack_options.md).
Type 'T' must be an instantiation of [basic_json](../basic_json.md)
or support [json_type_traits](../json_type_traits.md).
Type `ByteContainer` must be back insertable and have member type `value_type` with size exactly 8 bits (since 0.152.0.)
Any of the values types `int8_t`, `uint8_t`, `char`, `unsigned char` and `std::byte` (since C++17) are allowed.
(2) Writes a value of type T into a binary stream in the MessagePack data format, using the specified (or defaulted) [options](msgpack_options.md).
Type 'T' must be an instantiation of [basic_json](../basic_json.md)
or support [json_type_traits](../json_type_traits.md).
Functions (3)-(4) are identical to (1)-(2) except an [allocator_set](../allocator_set.md) is passed as an additional argument.
### Examples
#### MessagePack example
```cpp
#include <jsoncons/json.hpp>
#include <jsoncons_ext/msgpack/msgpack.hpp>
using namespace jsoncons;
using namespace jsoncons::msgpack;
int main()
{
ojson j1;
j1["zero"] = 0;
j1["one"] = 1;
j1["two"] = 2;
j1["null"] = null_type();
j1["true"] = true;
j1["false"] = false;
j1["max int64_t"] = (std::numeric_limits<int64_t>::max)();
j1["max uint64_t"] = (std::numeric_limits<uint64_t>::max)();
j1["min int64_t"] = (std::numeric_limits<int64_t>::lowest)();
j1["max int32_t"] = (std::numeric_limits<int32_t>::max)();
j1["max uint32_t"] = (std::numeric_limits<uint32_t>::max)();
j1["min int32_t"] = (std::numeric_limits<int32_t>::lowest)();
j1["max int16_t"] = (std::numeric_limits<int16_t>::max)();
j1["max uint16_t"] = (std::numeric_limits<uint16_t>::max)();
j1["min int16_t"] = (std::numeric_limits<int16_t>::lowest)();
j1["max int8_t"] = (std::numeric_limits<int8_t>::max)();
j1["max uint8_t"] = (std::numeric_limits<uint8_t>::max)();
j1["min int8_t"] = (std::numeric_limits<int8_t>::lowest)();
j1["max double"] = (std::numeric_limits<double>::max)();
j1["min double"] = (std::numeric_limits<double>::lowest)();
j1["max float"] = (std::numeric_limits<float>::max)();
j1["zero float"] = 0.0;
j1["min float"] = (std::numeric_limits<float>::lowest)();
j1["Key too long for small string optimization"] = "String too long for small string optimization";
std::vector<uint8_t> cont;
encode_msgpack(j1, cont);
ojson j2 = decode_msgpack<ojson>(cont);
std::cout << pretty_print(j2) << '\n';
}
```
Output:
```json
{
"zero": 0,
"one": 1,
"two": 2,
"null": null,
"true": true,
"false": false,
"max int64_t": 9223372036854775807,
"max uint64_t": 18446744073709551615,
"min int64_t": -9223372036854775808,
"max int32_t": 2147483647,
"max uint32_t": 4294967295,
"min int32_t": -2147483648,
"max int16_t": 32767,
"max uint16_t": 65535,
"min int16_t": -32768,
"max int8_t": 127,
"max uint8_t": 255,
"min int8_t": -128,
"max double": 1.79769313486232e+308,
"min double": -1.79769313486232e+308,
"max float": 3.40282346638529e+038,
"zero float": 0.0,
"min float": -3.40282346638529e+038,
"Key too long for small string optimization": "String too long for small string optimization"
}
```
### See also
[decode_msgpack](decode_msgpack) decodes a [MessagePack](http://msgpack.org/index.html) data format to a json value.
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