前言：
当前同学们对“ubuntu上jsoncpp”大致比较讲究，同学们都想要剖析一些“ubuntu上jsoncpp”的相关资讯。那么小编同时在网上汇集了一些对于“ubuntu上jsoncpp””的相关资讯，希望大家能喜欢，各位老铁们快快来学习一下吧！jsoncpp是c++读写json的一个工具库，十分小巧好用。但是其更新也比较快，有时变化较大。很多人可能还在使用Json::Reader::parse或者Json::FastWriter::write方法进行读写。如果使用较新版本的话会发现这些方法都已经是deprecated了，建议使用CharReaderBuilder和StreamWriterBuilder进行替换。下面就简单举个例子说明一下，更多详细内容请参看源码或者manual文档。
example.json文件内容
{
"name": "xiaoli",
"age": 25,
"hobbies": [
"pingpong",
"listen song",
{
"other": [
"eating noddles",
"reading books"
],
"lucky number": 26
}
]
}
测试代码如下：
#include <iostream>
#include <fstream>
#include <sstream>
#include <memory>
#include <json/json.h>
using namespace std;
/* example.json content
{
"name": "xiaoli",
"age": 25,
"hobbies": [
"pingpong",
"listen song",
{
"other": [
"eating noddles",
"reading books"
],
"lucky number": 26
}
]
}
*/
int main()
{
ifstream ifs("example.json");
// get file content by string
ostringstream os;
os << ifs.rdbuf();
string file_str = os.str();
os.clear(); // clear flags
os.str(""); // clear content
ifs.seekg(0); // reset position to 0
cout << "======= json file content is =======" << endl;
cout << file_str << endl;
cout << "======= test reading ========" << endl;
Json::CharReaderBuilder rbuilder;
rbuilder["collectComments"] = false;
Json::Value root;
JSONCPP_STRING errs;
// parse json document
bool ok = Json::parseFromStream(rbuilder, ifs, &root, &errs);
if (!ok) {
cout << "***** PARSE ERROR: " << errs << endl;
return -1;
}
else {
try {
cout << "***** READ SUCCEED." << endl;
cout << "name is " << root["name"].asString() << endl;
cout << "age is " << root["age"].asInt() << endl;
cout << "lucky number is "
<< root["hobbies"][2]["lucky number"].asInt()
<< endl;
}
catch (const Json::LogicError& ex) {
cout << "****** EXCEPTION CAUGHT in reading: " << ex.what() << endl;
}
}
cout << endl;
cout << "======= test writing ========" << endl;
// write json Object Value to file
Json::StreamWriterBuilder wbuilder;
wbuilder["commentStyle"] = "None";
wbuilder["indentation"] = " "; // or whatever you like
unique_ptr<Json::StreamWriter> writer(wbuilder.newStreamWriter());
try {
writer->write(root, &os);
}
catch (const exception& ex) {
cout << "****** EXCEPTION CAUGHT in writing: " << ex.what() << endl;
}
string json_str = os.str();
if (os.fail()) {
cout << "***** Write ERROR." << endl;
}
else {
cout << "***** Write SUCCEED." << endl;
}
cout << "writed string is:" << endl;
cout << json_str << endl;
}
编译运行命令如下（与jsoncpp安装位置有关，我安装在 /usr/local/{include, lib}）：
g++ --verbose -std=c++14 -Wall -Werror -Wextra $(pkg-config --cflags --libs jsoncpp) jsoncpp-example.cpp -o example
or
g++ --verbose -std=c++14 -Wall -Werror -Wextra -I/usr/local/include -L/usr/local/lib -ljsoncpp jsoncpp-example.cpp -o example
LD_LIBRARY_PATH=/usr/local/lib ./example
运行结果输出如下：
======= json file content is =======
{
"name": "xiaoli",
"age": 25,
"hobbies": [
"pingpong",
"listen song",
{
"other": [
"eating noddles",
"reading books"
],
"lucky number": 26
}
]
}
======= test reading ========
***** READ SUCCEED.
name is xiaoli
age is 25
lucky number is 26
======= test writing ========
***** Write SUCCEED.
writed string is:
{
"age" : 25,
"hobbies" :
[
"pingpong",
"listen song",
{
"lucky number" : 26,
"other" : [ "eating noddles", "reading books" ]
}
],
"name" : "xiaoli"
}
最后，与时俱进，少用deprecated方法，特别是对开源代码。
标签： #ubuntu上jsoncpp
