C++ Compile problem with WinHttp/Windows SDK

Question

Trying to compile a sample http class with the SDK, and getting some strange link errors... I am sure its something to do with a missing option, or directory...

I am no expert in c++ as you can see, but looking for any assistance.

I included my sample class. I also did install the Windows SDK. If you need any other information about my setups or anything, please ask. I'd prefer someone point me to a working WinHttp SDK sample project.

//START OF utils.cpp
#pragma once
#include "stdafx.h"

class http
{
public:
    http();
    ~http();

    std::string getText();

};
//END OF utils.cpp

---

//START OF utils.cpp
#include "stdafx.h"
#include "utils.h"

http::http()
{
}

http::~http()
{
}

std::string http::getText()
{
    DWORD dwSize = 0;
    DWORD dwDownloaded = 0;
    LPSTR pszOutBuffer;
    BOOL  bResults = FALSE;
    HINTERNET  hSession = NULL, 
        hConnect = NULL,
        hRequest = NULL;

    // Use WinHttpOpen to obtain a session handle.
    hSession = WinHttpOpen( L"WinHTTP Example/1.0",  
        WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
        WINHTTP_NO_PROXY_NAME, 
        WINHTTP_NO_PROXY_BYPASS, 0 );

    // Specify an HTTP server.
    if( hSession )
        hConnect = WinHttpConnect( hSession, L"www.microsoft.com",
        INTERNET_DEFAULT_HTTPS_PORT, 0 );

    // Create an HTTP request handle.
    if( hConnect )
        hRequest = WinHttpOpenRequest( hConnect, L"GET", NULL,
        NULL, WINHTTP_NO_REFERER, 
        WINHTTP_DEFAULT_ACCEPT_TYPES, 
        WINHTTP_FLAG_SECURE );

    // Send a request.
    if( hRequest )
        bResults = WinHttpSendRequest( hRequest,
        WINHTTP_NO_ADDITIONAL_HEADERS, 0,
        WINHTTP_NO_REQUEST_DATA, 0, 
        0, 0 );


    // End the request.
    if( bResults )
        bResults = WinHttpReceiveResponse( hRequest, NULL );

    // Keep checking for data until there is nothing left.
    if( bResults )
    {
        do 
        {
            // Check for available data.
            dwSize = 0;
            if( !WinHttpQueryDataAvailable( hRequest, &dwSize ) )
                printf( "Error %u in WinHttpQueryDataAvailable.\n",
                GetLastError( ) );

            // Allocate space for the buffer.
            pszOutBuffer = new char[dwSize+1];
            if( !pszOutBuffer )
            {
                printf( "Out of memory\n" );
                dwSize=0;
            }
            else
            {
                // Read the data.
                ZeroMemory( pszOutBuffer, dwSize+1 );

                if( !WinHttpReadData( hRequest, (LPVOID)pszOutBuffer, 
                    dwSize, &dwDownloaded ) )
                    printf( "Error %u in WinHttpReadData.\n", GetLastError( ) );
                else
                    printf( "%s", pszOutBuffer );

                // Free the memory allocated to the buffer.
                delete [] pszOutBuffer;
            }
        } while( dwSize > 0 );
    }


    // Report any errors.
    if( !bResults )
        printf( "Error %d has occurred.\n", GetLastError( ) );

    // Close any open handles.
    if( hRequest ) WinHttpCloseHandle( hRequest );
    if( hConnect ) WinHttpCloseHandle( hConnect );
    if( hSession ) WinHttpCloseHandle( hSession );

    return "";
}
//END OF utils.cpp

---

1>------ Build started: Project: winagent, Configuration: Debug Win32 ------
1>Compiling...
1>utils.cpp
1>Linking...
1>   Creating library C:\winagent\Debug\winagent.lib and object C:\winagent\Debug\winagent.exp
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpCloseHandle@4 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpReadData@16 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpQueryDataAvailable@8 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpReceiveResponse@8 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpSendRequest@28 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpOpenRequest@28 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpConnect@16 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>utils.obj : error LNK2019: unresolved external symbol __imp__WinHttpOpen@20 referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall http::getText(void)" (?getText@http@@QAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
1>C:\winagent\Debug\winagent.exe : fatal error LNK1120: 8 unresolved externals
1>Build log was saved at "file://c:\winagent\Debug\BuildLog.htm"
1>winagent - 9 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

If you check the MSDN reference for the WinHttp* functions you will see that you need to link with the library Winhttp.lib.

Open the project settings, select the linker options then 'input' and add WinHttp.lib to the 'Additional Dependencies' list.

Or you could put

#pragma comment(lib, "winhttp.lib")

(as previously mentioned) in your source code.

Answer 2

You need to link to winhttp.lib

Change the project settings or add this line to your .cpp file

#pragma comment(lib, "winhttp")

Answer 3

You've not added the WinHttp library to your link list.

Answer 4

Make sure you are linking with Winhttp.lib.