Jeeson

A json parsing library. Nothing special really. Got a json file you want to use in your program and your program is written in C? Well then give this one a go.

Resource

The json specification was the only needed resource to get an implementation up and running. It is short and concise, having excellent graph visualization to fully grasp the format. Easily a 10/10 as far as format grammar documentation goes.

Instructions

Building the project requires cmake. It is desirable to create a build directory to have a cleaner file tree. My personal choice is almost always bin.

mkdir bin
cd bin
cmake ..
make

Parser features [6/8]

• [X] objects
• [X] arrays
• [X] string
• [X] number
• [X] array
• [X] boolean
• [ ] escape characters and unicode
• [ ] null

Documentation

• To load a json file into your program and then print it.

struct json_object_t *object=json_to_object(path_to_json);
printf_object(*object, 0);

• To check if a json object contains a key. the has_key function returns the index of the key that can then be used to index into the internal key structure.

struct json_object_t *object=json_to_object(path_to_json);
char *key_to_look_for = "your";
ssize_t idx = has_key(object, key_to_look_for);
if (idx == -1) {
  printf("(◞‸◟)\n");
}else {
  printf("( ˶ˆᗜˆ˵ )\n");
}

• In order to get the value associate with a key in an object, one needs to know in advance what the type of the value is.

struct json_object_t *object=json_to_object(path_to_json);
char *key = "your";

// fetching string
char *mama = get_string(object, key);

// fetching number
double weight = get_number(object, key);

// fetching array element
struct json_array_t *mamas = get_array(object, key);
printf_array(*array, 0);

// fetching object element
struct json_object_t *obj = get_object(object, key);
printf_object(*obj, 0);

• Indexing values inside array values is similar to fetching values associated with keys in an object, any time you want to get a value from JSON you have to know in advance what the type of that data is to use the corresponding function.

struct json_object_t *object=json_to_object(path_to_json);
char *key = "your";

struct json_array_t *mamas = get_array(object, key);
printf_array(*array, 0);

size_t name_idx = 0;
size_t weight_idx = 1;
size_t kids_idx = 2;

// fetching string element
char *name = get_array_string_element(mamas, name_idx);

// fetching an infinitely big number element
long double weight = get_array_number_element(mamas, weight_idx);

// fetching object element
struct json_object_t *kids = get_array_object_element(mamas, kids_idx);

• Any memory, inevitably, must be freed.

struct json_object_t *object=json_to_object(path_to_json);
// ...
free_json_object(object);