Jsoncpp Use Experience

Jsoncpp the method to determine whether a field exists is as follows:

1) if (root["url"].type ()! = Json::nullvalue)

2) if (value["Sex"].isnull ())

Precautions

1) jsoncpp is a JSON library used by C + + to implement the syntax of JSON by overloading the brackets [], but because C + +

is a strongly typed language, jsoncpp in the implementation process, using a large number of assertions, if the type is encountered incorrectly

, the assertion is enforced, causing the program to exit

For example, pass the following string to the Jsoncpp

std::string strcontext = "Success": false, "MSG": "Gallium sentence switches arrival version ā æ 縞 ode:huoqushebeitongdaoshijianchuo11"

Json::reader read ();

Json::value Root;

if (NULL = = Read.parse (strcontext, Root)) return-1;

Although the string is not a proper JSON-formatted string, it will be parsed as well, resulting in a program that crashes, exits, and goes into the assertion, regardless of the field you use.

The solution is to specify strict JSON message parsing rules

std::string strcontext = "Success": false, "MSG": "Gallium sentence switches arrival version ā æ 縞 ode:huoqushebeitongdaoshijianchuo11"

Json::reader Read (Json::features::strictmode ());

Json::value Root;

if (NULL = = Read.parse (strcontext, Root)) return-1;

There won't be any anomalies like this.

Because Jsoncpp parses an illegal JSON, it is automatically fault-tolerant into character types. When a label is removed for a character type, the assert termination process is triggered.

Reference

Https://www.2cto.com/kf/201409/339350.html

http://blog.csdn.net/sxyizhiren/article/details/18625193

2) Json::value inside the function only Asint, asuint, and does not go to 64-bit integer function, so in the case of returning 64-bit integer, you can first convert to a string, using asstring, and then convert the string to 64-bit integer, indifferent night provides

One option is to convert to floating point, asdouble

Reference

Http://www.mamicode.com/info-detail-78967.html

Jsoncpp Use Experience