(MFC) Get the Last-Modified Date Before HTTP Download

Demonstrates how to send a HEAD request to get the last-modified date of a file on a web server (without downloading the file).

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

See Also: Using MFC CString in Chilkat

#include <CkHttp.h>
#include <CkHttpResponse.h>
#include <CkDateTime.h>
#include <CkDtObj.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkHttp http;

    CkHttpResponse *resp = http.GetHead("https://www.chilkatsoft.com/hamlet.xml");
    if (http.get_LastMethodSuccess() == false) {
        strOut.append(http.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Examine the response header.
    strOut.append(resp->header());
    strOut.append("\r\n");

    // Here is a sample response header:

    // 	Content-Length: 279658
    // 	Content-Type: text/xml
    // 	Last-Modified: Thu, 12 May 2016 15:14:08 GMT
    // 	Accept-Ranges: bytes
    // 	ETag: "c1cd8bee60acd11:0"
    // 	Server: Microsoft-IIS/8.5
    // 	X-Powered-By: ASP.NET
    // 	X-Powered-By-Plesk: PleskWin
    // 	Date: Thu, 25 Jul 2019 16:40:54 GMT

    // Get the Last-Modified header.
    const char *lastModStr = resp->getHeaderField("Last-Modified");
    // If the header exists...
    if (resp->get_LastMethodSuccess() == true) {
        // Parse the RFC822 format date/time string
        CkDateTime ckdt;
        ckdt.SetFromRfc822(lastModStr);

        // If we want to access individual date/time parts (in the local timezone)
        CkDtObj *dt = ckdt.GetDtObj(true);
        strOut.append("day/month/year = ");
        strOut.appendInt(dt->get_Day());
        strOut.append("/");
        strOut.appendInt(dt->get_Month());
        strOut.append("/");
        strOut.appendInt(dt->get_Year());
        strOut.append("\r\n");
        delete dt;
    }

    delete resp;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }