(MFC) Get the Index of a JSON Member

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
    }
}

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkString strOut;

    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}}";

    bool success = json.Load(jsonStr);
    if (success != true) {
        strOut.append(json.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        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.
    strOut.append("nameIndex = ");
    strOut.appendInt(nameIndex);
    strOut.append("\r\n");

    int thumbIndex = json.IndexOf("thumbnail");
    // The index of the "thumbnail" member is 2.
    strOut.append("thumbIndex = ");
    strOut.appendInt(thumbIndex);
    strOut.append("\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.
    strOut.append("fnameIndex = ");
    strOut.appendInt(fnameIndex);
    strOut.append("\r\n");

    // Get the "image" object.
    CkJsonObject *imageObj = json.ObjectOf("image");
    if (json.get_LastMethodSuccess() == false) {
        strOut.append("image object not found.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Now we can get the index of the "fname" object, because it is a direct
    // member of the "image" object:
    fnameIndex = imageObj->IndexOf("fname");
    strOut.append("fnameIndex = ");
    strOut.appendInt(fnameIndex);
    strOut.append("\r\n");

    delete imageObj;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }