(MFC) Get Size of File on Web Server

Demonstrates how to send a HEAD request to fetch information about a file on a web server, which hopefully includes the Content-Length in the response header.

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

See Also: Using MFC CString in Chilkat

#include <CkHttp.h>
#include <CkHttpResponse.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://nodejs.org/dist/v10.16.1/node-v10.16.1-win-x64.zip");
    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:

    // Date: Thu, 01 Aug 2019 12:47:27 GMT
    // Content-Type: application/zip
    // Content-Length: 17457922
    // Connection: keep-alive
    // Set-Cookie: __cfduid=da5b78dcdd8171683c5a578eb9c9f88c81564663647; expires=Fri, 31-Jul-20 12:47:27 GMT; path=/; domain=.nodejs.org; HttpOnly
    // Last-Modified: Wed, 31 Jul 2019 18:21:57 GMT
    // ETag: "5d41dc45-10a6302"
    // Accept-Ranges: bytes
    // Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
    // Server: cloudflare
    // CF-RAY: 4ff7ebb32ac4e1e2-ORD

    // Get the Content-Length header.
    const char *contentLengthStr = resp->getHeaderField("Content-Length");
    // If the header exists...
    if (resp->get_LastMethodSuccess() == true) {
        strOut.append("Content-Length: ");
        strOut.append(contentLengthStr);
        strOut.append("\r\n");
        // Your application can convert the contentLengthStr to an integer and then use it....
    }

    delete resp;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }