(C) 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).

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#include <C_CkHttp.h>
#include <C_CkHttpResponse.h>
#include <C_CkDateTime.h>
#include <C_CkDtObj.h>

void ChilkatSample(void)
    {
    HCkHttp http;
    HCkHttpResponse resp;
    const char *lastModStr;
    HCkDateTime ckdt;
    HCkDtObj dt;

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

    http = CkHttp_Create();

    resp = CkHttp_GetHead(http,"https://www.chilkatsoft.com/hamlet.xml");
    if (CkHttp_getLastMethodSuccess(http) == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        return;
    }

    // Examine the response header.
    printf("%s\n",CkHttpResponse_header(resp));

    // 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.
    lastModStr = CkHttpResponse_getHeaderField(resp,"Last-Modified");
    // If the header exists...
    if (CkHttpResponse_getLastMethodSuccess(resp) == TRUE) {
        // Parse the RFC822 format date/time string
        ckdt = CkDateTime_Create();
        CkDateTime_SetFromRfc822(ckdt,lastModStr);

        // If we want to access individual date/time parts (in the local timezone)
        dt = CkDateTime_GetDtObj(ckdt,TRUE);
        printf("day/month/year = %d/%d/%d\n",CkDtObj_getDay(dt),CkDtObj_getMonth(dt),CkDtObj_getYear(dt));
        CkDtObj_Dispose(dt);
    }

    CkHttpResponse_Dispose(resp);


    CkHttp_Dispose(http);
    CkDateTime_Dispose(ckdt);

    }