cJSON Tutorial

git clone https://github.com/DaveGamble/cJSON.git
 cd cJSON/
 mkdir build
 cd build/
 cmake ..
 sudo make install
 cd ..
 sudo ln -s /usr/local/lib/libcjson.so /usr/lib/libcjson.so
 sudo ln -s /usr/local/lib/libcjson.so.1 /usr/lib/libcjson.so.1
 sudo ln -s /usr/local/lib/libcjson.so.1.7.12 /usr/lib/libcjson.so.1.7.12
 gcc cJSONTestProgram.c -l cjson
 ./a.out

Planet:
Mars, 6.39e+23 kgs
Moon:
Phobos, 70 kms
Moon:
Deimos, 39 kms
satheesh@skyrdkdev:~/cJSON$ cat cJSONTestProgram.c

//src: https://spacesciencesoftware.wordpress.com/2013/09/10/a-good-way-to-read-json-with-c/

#include stdio.h
#include string.h
#include cjson/cJSON.h

int main(int argc, const char * argv[]) {
    /*{
        "name": "Mars",
        "mass": 639e21,
        "moons": [
            {
                "name": "Phobos",
                "size": 70
            },
            {
                "name": "Deimos",
                "size": 39
            }
        ]
    }*/
    char *strJson = "{\"name\" : \"Mars\",\"mass\":639e21,\"moons\":
    [{\"name\":\"Phobos\",\"size\":70},{\"name\":\"Deimos\",\"size\":39}]}";

    printf("Planet:\n");
    // First, parse the whole thing
    cJSON *root = cJSON_Parse(strJson);


    // Let's get some values
    char *name = cJSON_GetObjectItem(root, "name")->valuestring;
    double mass = cJSON_GetObjectItem(root, "mass")->valuedouble;


    printf("%s, %.2e kgs\n", name, mass); 
    // Note the format! %.2e will print a number with scientific notation and 2 decimals



    // Now let's iterate through the moons array
    cJSON *moons = cJSON_GetObjectItem(root, "moons");


    // Get the count
    int moons_count = cJSON_GetArraySize(moons);
    int i;


    for (i = 0; i < moons_count; i++) {
        printf("Moon:\n");


        // Get the JSON element and then get the values as before
        cJSON *moon = cJSON_GetArrayItem(moons, i);
        char *name = cJSON_GetObjectItem(moon, "name")->valuestring;
        int size = cJSON_GetObjectItem(moon, "size")->valueint;
        printf("%s, %d kms\n", name, size);
    }

    // Finally remember to free the memory!
    cJSON_Delete(root);
    return 0;
}
satheesh@skyrdkdev:~/cJSON$