json.h

json.h is a C header only library designed to make working with json in C as asthetically pleasing and ergonomic as possible. For example, defining a json structure using json.h could take the following form:

json_t root = JSON (
        { "foo", JSON_INT (100) },
        { "bar", JSON_STR ("Hello world") },
        { "baz",
          JSON_OBJ (
                  { "bat", JSON_BOOL (true) },
                  { "boop",
                    JSON_OBJ ({ "prob", JSON_FLT (0.5) }, {}
                              // each object must end with an empty pair
                              ) },
                  {} // each object must end with an empty pair
                  ) },
        { "bap", JSON_NULL },
        {} // each object must end with an empty pair
);

You can retrieve a value from the structure using json_get

json_value_t* baz_boop_prob = json_get (root, "baz.boop.prob");
assert (baz_boop_prob);
assert (baz_boop_prob->type == JSON_VAL_FLT);
assert (baz_boop_prob->num == 0.5);

This structure can be serialized to a string like so:

char json_str[1024];

json_serialize (&root, json_str, sizeof(json_str), NULL);

Or if you would rather allocate exactly the number of bytes needed (this walks the structure twice):

// count the number of bytes the string needs
size_t json_str_len = json_serialize (&root, NULL, 0, NULL);

// allocate and serialize
char* json_str = (char*)alloca (json_str_len); // use allocation method of choice
json_serialize (&root, json_str, json_str_len, NULL);

A serialized json string can then be parsed back into a json_t structure like so:

json_t* json = json_deserialize ((char*)json_str);

Be sure to null check json as null is returned if parsing fails.

Caveats

This library offers an incomplete json implementation. It does not (yet) support arrays, and other less common json attributes.

Requirements

To build and use this library will only require:

C/C++ toolchain

However, if you would like to contribute, or run tests, these additional tools are recommended:

Python3+
GNU make
doxygen
clang-format

Usage

The Makefile included at the repository root can be used to do almost everything you could want to do. This includes fetching, installing and building dependencies, building documentation and of course the software itself. Helpful make rules include the following.

test - Build and run the test suite
format - Run clang-format explicitly (normally executed as a pre-commit hook).
docs - Run Doxygen and build documentation.
clean - Delete all build artifacts.

mrpossoms/json.h

json.h

Caveats

Requirements

Usage