linking gdi

this pops

C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp/ccaAbaaa.o:hdc.cpp:(.text+0x39a): undefined reference to `CreateDIBSection@24'
collect2: ld returned 1 exit status



when I try to compile this, and it's been suggested that the way to solving it is to

"You need to link with gdi32.lib - I thin, with MinGW, that is libgdi32.a"



how do I do that?








#include <sstream>
#include <windows.h>
#include <iostream>
#include <vector>
#include <string.h>
#include <stdio.h>

using namespace std;


// save window and hdc hdc return are the same color?
// do they have the same picture?
// ie, what

void SaveWindow(HWND hwnd, const char* pName);
void savewindow ( HWND hwnd1, string string1 );
// save the window given hwnd


int main ()
{
     
     
     
     
     
      return 0;
}



void savewindow ( HWND hwnd1, string string1 )
{
      stringstream ss;
      ss << string1 << ".bmp";
      SaveWindow( hwnd1, ss.str().c_str());
}
     
     
void SaveWindow(HWND hwnd, const char* pName)
{
        BYTE* pDrawingSurfaceBits;
        RECT rc;
        HDC hDC = GetDC(hwnd);
        BITMAPINFOHEADER BMIH;

        GetWindowRect(hwnd,&rc);

        BMIH.biSize = sizeof(BITMAPINFOHEADER);
        BMIH.biBitCount = 24;
        BMIH.biPlanes = 1;
        BMIH.biCompression = BI_RGB;
        BMIH.biWidth = rc.right - rc.left;
        BMIH.biHeight = rc.bottom - rc.top;
        BMIH.biSizeImage = ((((BMIH.biWidth * BMIH.biBitCount)
                           + 31) & ~31) >> 3) * BMIH.biHeight;
        HBITMAP hDrawingSurface = CreateDIBSection(hDC,
                 (CONST BITMAPINFO*)&BMIH, DIB_RGB_COLORS,
                 (void**)&pDrawingSurfaceBits, NULL, 0);
        ReleaseDC(hwnd,hDC);

       
        //Create a new file for writing
        FILE *pFile = fopen(pName, "wb");
        if(pFile == NULL)
        {
            MessageBox(NULL,"Cannot open file","Error",MB_OK);
            return;
        }
        BITMAPFILEHEADER bmfh;
        int nBitsOffset = sizeof(BITMAPFILEHEADER) + BMIH.biSize;
        LONG lImageSize = BMIH.biSizeImage;
        LONG lFileSize = nBitsOffset + lImageSize;
        bmfh.bfType = 'B'+('M'<<8);
        bmfh.bfOffBits = nBitsOffset;
        bmfh.bfSize = lFileSize;
        bmfh.bfReserved1 = bmfh.bfReserved2 = 0;
        //Write the bitmap file header
        UINT nWrittenFileHeaderSize = fwrite(&bmfh, 1,
                     sizeof(BITMAPFILEHEADER), pFile);
        //And then the bitmap info header
        UINT nWrittenInfoHeaderSize = fwrite(&BMIH,
               1, sizeof(BITMAPINFOHEADER), pFile);
        //Finally, write the image data itself
        //-- the data represents our drawing
        UINT nWrittenDIBDataSize =
             fwrite(pDrawingSurfaceBits, 1, lImageSize, pFile);

        fclose(pFile);
}