(MFC) Demonstrates how to Handle Large Integers in JSON

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Demonstrates how to handle large integers in JSON. (Integers larger than what can fit in a 32-bit signed integer.)

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;

    // Let's say your JSON has this:

    // {
    // 	"id": 20000000001234567
    // }

    CkJsonObject json;

    bool success = json.LoadFile("qa_data/json/large_int.json");
    if (success == false) {
        strOut.append(json.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // The integer is too large for a 32-bit signed integer that is returned by IntOf.
    // The result will be something that wrapped around and could be negative.
    // In this case it would be: -543893881
    int id = json.IntOf("id");
    strOut.append("id: ");
    strOut.appendInt(id);
    strOut.append("\r\n");

    // The solution is to read the integer value as a string, and then use the features in your programming language
    // to convert from a string to a 64-bit integer.
    // 
    // Alternatively, you may wish to simply hold the value as a string.  If, for example, the integer simply references
    // an order ID, an account ID, etc., then there's no need to convert to an integer value.  You're not going to be doing
    // mathematical operations on it anyway.  This is usually the case for large integers -- they typically exist
    // in JSON as an account ID.

    // You can get any JSON value as a string:
    const char *accountId = json.stringOf("id");
    strOut.append("accountId: ");
    strOut.append(accountId);
    strOut.append("\r\n");

    // Sample output:

    // id: -543893881
    // accountId: 20000000001234567


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }