JSON construction and analysis

The default project already includes the open source cppjson library, which can be used directly.

Steps for usage

Quote header file

#include "json/json.h"

Construct JSON string

Json::Value root;
//Add integer value
root["int"] = 1;
//Add string
root["str"] = "hello";

/*Due to the accuracy printing problem of floating-point numbers, it is not recommended to use them, try to convert to integers*/
root["float"] = 3.14f;

//Add array 
Json::Value array;
root["array"] = array;

//json nesting
Json::Value sub;
sub["int"] = 1;
sub["str"] = "sub str value";
root["subJson"] = sub;

LOGD("The generated json string is: ");
LOGD("%s", root.toStyledString().c_str());

Parse JSON

//Parse json
Json::Reader reader;
Json::Value root2;
//For convenience, the constructed json string is used as the input for parsing json
std::string test_json_string = root.toStyledString();
if (reader.parse(test_json_string, root2, false)) {
  LOGD("Analysis successful");
  /*When parsing json, be sure to check the legitimacy of the input more to avoid program crash caused by illegal input.*/
  if (root2.isMember("int")) {
    LOGD("int = %d", root2["int"].asInt());
  if (root2.isMember("str")) {
    LOGD("str = %s", root2["str"].asString().c_str());
  if (root2.isMember("array")) {
    Json::Value obj = root2["array"];
    if (obj.isArray()) {
      for (Json::ArrayIndex i = 0; i < obj.size(); ++i) {
        LOGD("array: %s", obj[i].asString().c_str());
  if (root2.isMember("subJson")) {
    Json::Value sub = root2["subJson"];
    if (sub.isObject()) {
      if (sub.isMember("int")) {
        LOGD("subJson int = %d", sub["int"].asInt());
      if (sub.isMember("str")) {
        LOGD("subJson str = %s", sub["str"].asString().c_str());
powered by Gitbooklast modified: 2021-05-28 12:00:31

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