Bmp read out only red value

[lamko]

People,

I have a little problem and I don't seem to get. I've seen examples that worked this way but mine won't.

typedef struct
{
    BYTE  rgbtBlue;
    BYTE  rgbtGreen;
    BYTE  rgbtRed;
} __attribute__((__packed__))
RGBTRIPLE;

    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
    {
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
            // temporary storage
            RGBTRIPLE triple;

            // read RGB triple from infile
            fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
            
            printf("%x\n",triple.rgbtRed);

            // write RGB triple to outfile
            fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
        }

With this it seem to compile fine and seems to get only the red value.

But if I want to change printf("%x\n",triple.rgbtRed); to something like this :

            if (triple.rgbtRed != 0x00)
                triple.rgbtred = 0x00;

I'll get a compile error :

error: ‘RGBTRIPLE’ has no member named ‘rgbtred’

If searched on google for the error message but the results I got were way to complicated.

[Salem]

> error: ‘RGBTRIPLE’ has no member named ‘rgbtred’
Well the Red in your struct has a capital-R

[lamko]

I'm a shamed, because I had lots of errors and didnt know when to use -> or when to use . So I just was using some trial and error. But It seem it had nothing to do with that

[Salem]

BMP file format - Wikipedia, the free encyclopedia
Unless your width is always a multiple of 4, there is padding at the end of each scan line, which your code fails to take into account.

Plus you don't show how you open either file, or how you determine the width/height, or how you "seeked" to the start of the pixel data.

Nor do you check fread/fwrite for errors.

[lamko]

You're right, I didn't post that code because I'm sure that there wasnt a problem. All the things you mentioned are all there.
Thx for the quick reply, that wiki page I have also used a lot and is sure an excellent piece of info.