int main() 
{ 
    /* Declare the image */  
    gdImagePtr im;  
    /* Declare output files */  
    FILE *pngout, *jpegout; 
    /* Declare color indexes */
    int black;  int white;
    /* Allocate the image: 64 pixels across by 64 pixels tall */

    im = gdImageCreate(64, 64);
    /* Allocate the color black (red, green and blue all minimum).    Since this is the first color in a new image, it will    be the background color. */
    black = gdImageColorAllocate(im, 0, 0, 0);
    /* Allocate the color white (red, green and blue all maximum). */
    white = gdImageColorAllocate(im, 255, 255, 255);
    /* Draw a line from the upper left to the lower right,    using white color index. */
    gdImageLine(im, 0, 0, 63, 63, white);
    /* Open a file for writing. "wb" means "write binary", important    under MSDOS, harmless under Unix. */
    pngout = fopen("test.png", "wb");
    /* Do the same for a JPEG-format file. */
    jpegout = fopen("test.jpg", "wb");
    /* Output the image to the disk file in PNG format. */
    gdImagePng(im, pngout);
    /* Output the same image in JPEG format, using the default    JPEG quality setting. */
    gdImageJpeg(im, jpegout, -1);   /* Close the files. */
    fclose(pngout);
    fclose(jpegout);  
    /* Destroy the image in memory. */
    gdImageDestroy(im);
}