1.说明与安装
说明:
c++ json字符解析
安装:
sudo apt-get install libjsoncpp-dev
编译依赖
pkg-config --cflags --libs jsoncpp
-I/usr/include/jsoncpp -ljsoncpp
编译选项: -I/usr/include/jsoncpp
连接选项: -ljsoncpp
2.实例
1.代码
1_jsonCpp_解析字符串_增.删.改.查.保存.cc
c++
#include <iostream>
#include <fstream>
#include <memory>
#include <json/json.h>
// 假设我们有一个JSON字符串或文件内容
std::string json_data = R"({
"name": "John Doe",
"age": 30,
"city": "New York",
"hobbies": ["reading", "gaming"]
})";
void parse_and_modify_json()
{
// 1.解析JSON字符串
Json::Value root;
Json::CharReaderBuilder builder;
std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
JSONCPP_STRING err;
bool parsingSuccessful = reader->parse(json_data.c_str(), json_data.c_str() + json_data.size(), &root, &err);
if (!parsingSuccessful)
{
std::cout << "Failed to parse JSON: " << std::endl;
return;
}
// 2.改: 修改JSON数据
root["name"] = "Jane Doe"; // 修改名字
root["age"] = 31; // 修改年龄
root["hobbies"][0] = "programming"; // 替换第一个爱好
// 添加新的键值对
root["job"] = "Software Engineer";
// 3.查
std::string name = root["name"].asString();
int age = root["age"].asInt();
std::cout << "Name: " << name << std::endl;
std::cout << "Age: " << age << std::endl;
// 4.转为string
bool shouldUseOldWay = false; //使用旧版本的API
if (shouldUseOldWay)
{
Json::FastWriter writer;
const std::string json_file = writer.write(root);
std::cout <<"old way ---\n"<< json_file << std::endl;
}
else
{
Json::StreamWriterBuilder builder;
const std::string json_file = Json::writeString(builder, root);
std::cout <<"new way ---\n"<< json_file << std::endl;
}
// 5.写入文件
std::ofstream outfile("output.json");
if (outfile.is_open())
{
Json::StreamWriterBuilder builder;
builder["commentStyle"] = "None";
builder["indentation"] = " "; // 增加缩进
std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
writer->write(root, &outfile);
}
outfile.close();
}
int main(void)
{
parse_and_modify_json();
return 0;
}
2.scons构建
SConstruct
python
## 模板1
import os
env = Environment()
env["PROGSUFFIX"] = ".out" # 可执行后缀.out
env["CCFLAGS"] = " -g3 -O0 -Wall" # gdb 调试开关
env.MergeFlags(
[
"!pkg-config --cflags --libs jsoncpp",
]
)
src_list = [
"1_jsonCpp_解析字符串_增.删.改.查.保存.cc",
]
for src in src_list:
env.Program(Split(src))
scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
g++ -o 1_jsonCpp_解析字符串_增.删.改.查.保存.o -c -g3 -O0 -Wall -I/usr/include/jsoncpp 1_jsonCpp_解析字符串_增.删.改.查.保存.cc
g++ -o 1_jsonCpp_解析字符串_增.删.改.查.保存.out 1_jsonCpp_解析字符串_增.删.改.查.保存.o -ljsoncpp
scons: done building targets.
3.运行
./1_jsonCpp_解析字符串_增.删.改.查.保存.out
Name: Jane Doe
Age: 31
new way ---
{
"age" : 31,
"city" : "New York",
"hobbies" :
[
"programming",
"gaming"
],
"job" : "Software Engineer",
"name" : "Jane Doe"
}
建议使用gdb调试运行,查看代码流程.
3.其它实例
2_jsonCpp_从文件读取.cc
可以git clone https://gitee.com/zero2200/3_cpp-practice.git,
vscode 打开代码, F5 gdb调试运行