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Most people do not understand the knowledge points of this article, "CAccord + QT how to achieve parsing JSON files", so the editor summarizes the following contents, detailed contents, clear steps, and has a certain reference value. I hope you can get something after reading this article. Let's take a look at this article, "how to achieve the resolution of JSON files with QT".

JSON is a lightweight data exchange format, which is based on a subset of ECMAScript. It uses a text format that is completely independent of the programming language to store and represent data. The concise and clear hierarchical structure makes JSON an ideal data exchange language. Qt library provides complete class support for related operations of JSON.

Create a parsing file named config.json. We will parse each parameter in the JSON file in turn through code. The specific parsing code is as follows:

{"blog": "https://www.cnblogs.com/lyshark"," enable ": true," status ": 1024," GetDict ": {" address ":" 192.168.1.1 "," username ":" root "," password ":" 123456 "," update ":" 2020-09-26 "}," GetList ": "ObjectInArrayJson": {"One": ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"], "Two": ["Sunday", "Monday", "Tuesday"]}, "ArrayJson": [["192.168.1.1", "root", "22"], ["192.168.1.2", "root" "23"], ["192.168.1.3", "root", "24"], ["192.168.1.4", "root", "25"], ["192.168.1.5", "root", "26"]], "ObjectJson": [{"address": "192.168.1.1", "username": "admin"} {"address": "192.168.1.2", "username": "root"}, {"address": "192.168.1.3", "username": "lyshark"}], "ObjectArrayJson": [{"uname": "root", "ulist": [1, uname, 3, 4, 5]}, {"uname": "lyshark", "ulist": [11, 22, 3, 4, 5, 6, 6, 7, 899] "NestingObjectJson": [{"uuid": "1001", "basic": {"lat": "12.657", "lon": "55.789"}}, {"uuid": "1002" "basic": {"lat": "31.24", "lon": "25.55"}], "ArrayNestingArrayJson": [{"telephone": "1323344521" "path": [[11.5, 22.4, 56.9], [19.4, 34.6, 44.7]]}]}

To modify the node elements specified under the single-layer root node, the principle of modification is to read in memory replacement and write all to the file.

/ / read JSON text / / https://www.cnblogs.com/lysharkQString readonly_string (QString file_path) {QFile this_file_ptr (file_path); if (false = = this_file_ptr.exists ()) {return "None";} if (false = = this_file_ptr.open (QIODevice::ReadOnly | QIODevice::Text)) {return "None" } QString string_value = this_file_ptr.readAll (); this_file_ptr.close (); return string_value;} / write JSON to file bool writeonly_string (QString file_path, QString file_data) {QFile this_file_ptr (file_path); if (false = = this_file_ptr.open (QIODevice::WriteOnly | QIODevice::Text)) {return false;} QByteArray write_byte = file_data.toUtf8 () This_file_ptr.write (write_byte,write_byte.length ()); this_file_ptr.close (); return true;} int main (int argc, char * argv []) {QCoreApplication a (argc, argv); / / read the file QString readonly_config = readonly_string ("d:/config.json"); / / start parsing and return QJsonDocument object or return null QJsonParseError err_rpt QJsonDocument root_document = QJsonDocument::fromJson (readonly_config.toUtf8 (), & err_rpt); if (err_rpt.error! = QJsonParseError::NoError & &! root_document.isNull ()) {return 0;} / get the root node QJsonObject root = root_document.object (); / / modify the child node root ["blog"] = "https://www.baidu.com";" under the root node Root ["enable"] = false; root ["status"] = 2048; / / set object as the main object of this document root_document.setObject (root); / / Compact mode output / / https://www.cnblogs.com/lyshark QByteArray root_string_compact = root_document.toJson (QJsonDocument::Compact); std::cout

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