C++

Get the Index of a JSON Member

See more JSON Examples

This example demonstrates how to get the index of a given member by name.

{
  "name": "donut",
  "image":
    {
    "fname": "donut.jpg",
    "w": 200,
    "h": 200
    },
  "thumbnail":
    {
    "fname": "donutThumb.jpg",
    "w": 32,
    "h": 32
    }
}

C++

#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkJsonObject json;

    // This is the above JSON with whitespace chars removed (SPACE, TAB, CR, and LF chars).
    // The presence of whitespace chars for pretty-printing makes no difference to the Load
    // method. 
    const char *jsonStr = "{\"name\": \"donut\",\"image\":{\"fname\": \"donut.jpg\",\"w\": 200,\"h\": 200},\"thumbnail\":{\"fname\": \"donutThumb.jpg\",\"w\": 32,\"h\": 32}}";

    success = json.Load(jsonStr);
    if (success == false) {
        std::cout << json.lastErrorText() << "\r\n";
        return;
    }

    // The top-level JSON object has three members: name, image, and thumbnail.
    int nameIndex = json.IndexOf("name");
    // The index of the "name" member is 0.
    std::cout << "nameIndex = " << nameIndex << "\r\n";

    int thumbIndex = json.IndexOf("thumbnail");
    // The index of the "thumbnail" member is 2.
    std::cout << "thumbIndex = " << thumbIndex << "\r\n";

    // The "fname" member is NOT a direct member of the top-level JSON object.
    // It is a member of a nested object.  If we try to get the index of this
    // member using the top-level JSON object, it is not found (and returns -1).
    int fnameIndex = json.IndexOf("fname");
    // The fnameIndex is -1 (not found).  This is correct.
    std::cout << "fnameIndex = " << fnameIndex << "\r\n";

    // Get the "image" object.
    CkJsonObject imageObj;
    json.ObjectOf2("image",imageObj);

    // Now we can get the index of the "fname" object, because it is a direct
    // member of the "image" object:
    fnameIndex = imageObj.IndexOf("fname");
    std::cout << "fnameIndex = " << fnameIndex << "\r\n";
    }