Ubuntu 編譯 cJSON

reference: https://github.com/DaveGamble/cJSON

Configuration

$git clone https://github.com/soniah/gosnmp.git
$cd cJSON
$mkdir build
$cd build
$cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local/cjson
$make
$sudo make install

Example Code

Parser JSON string

#include<stdio.h>
#include<json-c/json.h>

#define EXAMPLE_JSON    "./example.json"
#define NULL_NULL       "NULL"
#define BOOL_BOOLEAN    "BOOLEAN"
#define STR_STRING      "STRING"
#define NUM_INTEGER     "NUMBER"
#define NUM_DOUBLE      "DOUBLE"
#define ARR_ARRAY       "ARRAY"
#define OBJ_OBJECT      "OBJECT"
#define NULL_MEMBER_NULL    "MEMBER_NULL"
#define BOOL_MEMBER_BOOLEAN "MEMBER_BOOLEAN"
#define STR_MEMBER_STRING   "MEMBER_STRING"
#define NUM_MEMBER_INTEGER  "MEMBER_NUMBER"
#define NUM_MEMBER_DOUBLE   "MEMBER_DOUBLE"
#define ARR_MEMBER_ARRAY    "MEMBER_ARRAY"

int write_to_json_file(char* filename)
{
    int ret = 0;
    json_object *json_obj = NULL;
    json_object *array_obj = NULL;
    json_object *new_obj = NULL;
    json_object *tmp_obj = NULL;
    json_object *tmp1_obj = NULL;

    //new a base object
    json_obj = json_object_new_object();
    if (!json_obj)
    {
        printf("Cannot create object\n");
        ret = -1;
        goto error;
    }

    //new a null
    json_object_object_add(json_obj, NULL_NULL, NULL);

    //new a boolean
    tmp_obj = json_object_new_boolean(1);
    if (!tmp_obj)
    {
        printf("Cannot create boolean object for %s\n", BOOL_BOOLEAN);
        ret = -1;
        goto error;
    }
    json_object_object_add(json_obj, BOOL_BOOLEAN, tmp_obj);
    tmp_obj = NULL;

    //new a string
    tmp_obj = json_object_new_string("string");
    if (!tmp_obj)
    {
        printf("Cannot create string object for %s\n", STR_STRING);
        ret = -1;
        goto error;
    }
    json_object_object_add(json_obj, STR_STRING, tmp_obj);
    tmp_obj = NULL;

    //new a integer
    tmp_obj = json_object_new_int(100);
    if (!tmp_obj)
    {
        printf("Cannot create number object for %s\n", NUM_INTEGER);
        ret = -1;
        goto error;
    }
    json_object_object_add(json_obj, NUM_INTEGER, tmp_obj);
    tmp_obj = NULL;

    //new a double
    tmp_obj = json_object_new_double(3.1415926);
    if (!tmp_obj)
    {
        printf("Cannot create double object for %s\n", NUM_DOUBLE);
        ret = -1;
        goto error;
    }
    json_object_object_add(json_obj, NUM_DOUBLE, tmp_obj);
    tmp_obj = NULL;

    //new a array
    array_obj = json_object_new_array();
    if (!array_obj)
    {
        printf("Cannot create array object\n");
        ret = -1;
        goto error;
    }

    //new a string and add to the array
    new_obj = json_object_new_string("str1");
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //new a string and add to the array
    new_obj = json_object_new_string("str2");
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //new a string and add to the array
    new_obj = json_object_new_string("str3");
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //add array to the base object
    json_object_object_add(json_obj, ARR_ARRAY, array_obj);
    array_obj = NULL;

    //new an object
    tmp_obj = json_object_new_object();
    if (!tmp_obj)
    {
        printf("Cannot create object\n");
        ret = -1;
        goto error;
    }

    //add a null to the object
    json_object_object_add(tmp_obj, NULL_MEMBER_NULL, NULL);

    //new a boolean and add to the object
    tmp1_obj = json_object_new_boolean(0);
    if (!tmp1_obj)
    {
        printf("Cannot create boolean object for %s\n", BOOL_MEMBER_BOOLEAN);
        ret = -1;
        goto error;
    }
    json_object_object_add(tmp_obj, BOOL_MEMBER_BOOLEAN, tmp1_obj);
    tmp1_obj = NULL;

    //new a string and add to the object
    tmp1_obj = json_object_new_string("string");
    if (!tmp1_obj)
    {
        printf("Cannot create string object for %s\n", STR_MEMBER_STRING);
        ret = -1;
        goto error;
    }
    json_object_object_add(tmp_obj, STR_MEMBER_STRING, tmp1_obj);
    tmp1_obj = NULL;

    //new a integer and add to the object
    tmp1_obj = json_object_new_int(200);
    if (!tmp1_obj)
    {
        printf("Cannot create number object for %s\n", NUM_MEMBER_INTEGER);
        ret = -1;
        goto error;
    }
    json_object_object_add(tmp_obj, NUM_MEMBER_INTEGER, tmp1_obj);
    tmp1_obj = NULL;

    //new a double and add to the object
    tmp1_obj = json_object_new_double(0.123456789);
    if (!tmp1_obj)
    {
        printf("Cannot create double object for %s\n", NUM_MEMBER_DOUBLE);
        ret = -1;
        goto error;
    }
    json_object_object_add(tmp_obj, NUM_MEMBER_DOUBLE, tmp1_obj);
    tmp1_obj = NULL;

    //new a array
    array_obj = json_object_new_array();
    if (!array_obj)
    {
        printf("Cannot create array object\n");
        ret = -1;
        goto error;
    }

    //new a integer and add to array
    new_obj = json_object_new_int(1);
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_MEMBER_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //new a integer and add to array
    new_obj = json_object_new_int(2);
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_MEMBER_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //new a integer and add to array
    new_obj = json_object_new_int(3);
    if (!new_obj)
    {
        printf("Cannot create string object for %s\n", ARR_MEMBER_ARRAY);
        ret = -1;
        goto error;
    }
    json_object_array_add(array_obj, new_obj);
    new_obj = NULL;

    //add array to the object
    json_object_object_add(tmp_obj, ARR_MEMBER_ARRAY, array_obj);
    array_obj = NULL;

    //add the object to base object
    json_object_object_add(json_obj, OBJ_OBJECT, tmp_obj);
    tmp_obj = NULL;

    //write the base object to write.json
    json_object_to_file(filename, json_obj);

error:
    json_object_put(tmp1_obj);
    json_object_put(tmp_obj);
    json_object_put(new_obj);
    json_object_put(array_obj);
    json_object_put(json_obj);

    return ret;
}

int read_from_json_file(char *filename)
{
    int ret = 0;
    json_object *test_obj = NULL;
    json_object *tmp_obj = NULL;
    json_object *tmp1_obj = NULL;
    json_object *tmp2_obj = NULL;

    //get json object from file
    test_obj = json_object_from_file(filename);
    if (!test_obj)
    {
        printf("Cannot open %s\n", filename);
        ret = -1;
        goto error;
    }

    //get null
    tmp_obj = json_object_object_get(test_obj, NULL_NULL);
    if (tmp_obj)
    {
        printf("Cannot get %s object\n", NULL_NULL);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", NULL_NULL, "null");

    //get boolean
    tmp_obj = json_object_object_get(test_obj, BOOL_BOOLEAN);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", BOOL_BOOLEAN);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", BOOL_BOOLEAN, ((json_object_get_boolean(tmp_obj))?("TRUE"):("FALSE")));

    //get string
    tmp_obj = json_object_object_get(test_obj, STR_STRING);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", STR_STRING);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", STR_STRING, json_object_get_string(tmp_obj));

    //get integer
    tmp_obj = json_object_object_get(test_obj, NUM_INTEGER);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", NUM_INTEGER);
        ret = -1;
        goto error;
    }
    printf("%s = %d\n", NUM_INTEGER, json_object_get_int(tmp_obj));

    //get double
    tmp_obj = json_object_object_get(test_obj, NUM_DOUBLE);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", NUM_DOUBLE);
        ret = -1;
        goto error;
    }
    printf("%s = %F\n", NUM_DOUBLE, json_object_get_double(tmp_obj));

    //get array
    tmp_obj = json_object_object_get(test_obj, ARR_ARRAY);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", ARR_ARRAY);
        ret = -1;
        goto error;
    }
    //get the length of the array
    printf("%s size = %d\n", ARR_ARRAY, json_object_array_length(tmp_obj));

    //get the value of array[0]
    tmp1_obj = json_object_array_get_idx(tmp_obj, 0);
    printf("%s[0] = %s\n", ARR_ARRAY, json_object_get_string(tmp1_obj));

    //get the value of array[1]
    tmp1_obj = json_object_array_get_idx(tmp_obj, 1);
    printf("%s[1] = %s\n", ARR_ARRAY, json_object_get_string(tmp1_obj));

    //get the value of array[2]
    tmp1_obj = json_object_array_get_idx(tmp_obj, 2);
    printf("%s[2] = %s\n", ARR_ARRAY, json_object_get_string(tmp1_obj));

    //get object
    tmp_obj = json_object_object_get(test_obj, OBJ_OBJECT);
    if (!tmp_obj)
    {
        printf("Cannot get %s object\n", OBJ_OBJECT);
        ret = -1;
        goto error;
    }

    //get null within a object
    tmp1_obj = json_object_object_get(tmp_obj, NULL_MEMBER_NULL);
    if (tmp1_obj)
    {
        printf("Cannot get %s object\n", NULL_MEMBER_NULL);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", NULL_MEMBER_NULL, "null");

    //get boolean within a object
    tmp1_obj = json_object_object_get(tmp_obj, BOOL_MEMBER_BOOLEAN);
    if (!tmp1_obj)
    {
        printf("Cannot get %s object\n", BOOL_MEMBER_BOOLEAN);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", BOOL_MEMBER_BOOLEAN, ((json_object_get_boolean(tmp1_obj))?("TRUE"):("FALSE")));

    //get string within a object
    tmp1_obj = json_object_object_get(tmp_obj, STR_MEMBER_STRING);
    if (!tmp1_obj)
    {
        printf("Cannot get %s object\n", STR_MEMBER_STRING);
        ret = -1;
        goto error;
    }
    printf("%s = %s\n", STR_MEMBER_STRING, json_object_get_string(tmp1_obj));

    //get integer within a object
    tmp1_obj = json_object_object_get(tmp_obj, NUM_MEMBER_INTEGER);
    if (!tmp1_obj)
    {
        printf("Cannot get %s object\n", NUM_MEMBER_INTEGER);
        ret = -1;
        goto error;
    }
    printf("%s = %d\n", NUM_MEMBER_INTEGER, json_object_get_int(tmp1_obj));

    //get double within a object
    tmp1_obj = json_object_object_get(tmp_obj, NUM_MEMBER_DOUBLE);
    if (!tmp1_obj)
    {
        printf("Cannot get %s object\n", NUM_MEMBER_DOUBLE);
        ret = -1;
        goto error;
    }
    printf("%s = %F\n", NUM_MEMBER_DOUBLE, json_object_get_double(tmp1_obj));

    //get array within a object
    tmp1_obj = json_object_object_get(tmp_obj, ARR_MEMBER_ARRAY);
    if (!tmp1_obj)
    {
        printf("Cannot get %s object\n", ARR_MEMBER_ARRAY);
        ret = -1;
        goto error;
    }
    //get the length of the array within a object
    printf("%s size = %d\n", ARR_MEMBER_ARRAY, json_object_array_length(tmp1_obj));

    //get the value of array[0] within a object
    tmp2_obj = json_object_array_get_idx(tmp1_obj, 0);
    printf("%s[0] = %d\n", ARR_MEMBER_ARRAY, json_object_get_int(tmp2_obj));

    //get the value of array[0] within a object
    tmp2_obj = json_object_array_get_idx(tmp1_obj, 1);
    printf("%s[1] = %d\n", ARR_MEMBER_ARRAY, json_object_get_int(tmp2_obj));

    //get the value of array[0] within a object
    tmp2_obj = json_object_array_get_idx(tmp1_obj, 2);
    printf("%s[2] = %d\n", ARR_MEMBER_ARRAY, json_object_get_int(tmp2_obj));

error:
    json_object_put(test_obj);

    return ret;
}

int main(int argc, char *argv[])
{
    int ret = 0;
    ret = write_to_json_file(EXAMPLE_JSON);
    if (ret != 0)
        printf("Fail to write a json file\n");

    ret = read_from_json_file(EXAMPLE_JSON);
    if (ret != 0)
        printf("Fail to read a json file\n");

    return 0;
}

Composer JSON string

Build and Execute

CMakelists File

//CMakelists.txt
cmake_minimum_required(VERSION 2.8)

# use folder name as project name
get_filename_component(ProjectId ${CMAKE_CURRENT_SOURCE_DIR} NAME)
string(REPLACE " " "_" ProjectId ${ProjectId})
project(${ProjectId})

set(CMAKE_BUILE_TYPE DEBUG)
set(CMAKE_C_FLAGS_DEBUG   "-O0 -g -Wall" )      # Debug not optimize
set(CMAKE_C_FLAGS_RELEASE "-O2 -DNDEBUG " )     # release optimeze

set(CMAKE_CXX_FLAGS_DEBUG   "-O0 -g -Wall" )    # Debug not optimize
set(CMAKE_CXX_FLAGS_RELEASE "-O2 -DNDEBUG " )   # release optimeze

#set(EXECUTABLE_OUTPUT_PATH "${CMAKE_CURRENT_LIST_DIR}")
set(EXECUTABLE_OUTPUT_PATH "${CMAKE_CURRENT_BINARY_DIR}")

message(STATUS "Project: ${ProjectId}")
message(STATUS "Project Directory: ${PROJECT_SOURCE_DIR}")
message(STATUS "Source Directory: ${CMAKE_CURRENT_LIST_DIR}/src")
message(STATUS "Output Directory: ${CMAKE_CURRENT_BINARY_DIR}")

# source code
aux_source_directory(${CMAKE_CURRENT_LIST_DIR}/src DIR_SRC)

# include
include_directories(${CMAKE_CURRENT_LIST_DIR}/include /usr/local/cjson/include)

# library ${CMAKE_CURRENT_LIST_DIR}/lib
link_directories(/usr/local/cjson/lib)

# build
message(STATUS "Source Files: ${DIR_SRC}")
add_executable(${PROJECT_NAME}.out ${DIR_SRC})
target_link_libraries(${PROJECT_NAME}.out -lcjson)

build and run

$mkdir build
$cd build
$cmake ..
$make
$./a.out