Command line arguments and arrays

[fatinez]

I need to make a 2-D array based on command line argumnets.

The program is supposed to compress an image in raw format. The command line is: compress filename width height

I have:

int main (int argc, char* argv[]){

        int width, height;
        FILE* fp;
        char image[][];

        if(argc != 4) message();
        width = atoi(argv[2]);
        height = atoi(argv[3]);

        
        return(0);
}

How can I set the width and height of the image array?
Any help would be appreciated and I hope I'm not just being stupid. Thanks.

Oh, and one more question while I'm here:
How can I modify values bit-by-bit. Thanks again

[Hammer]

>>How can I set the width and height of the image array?
Use malloc(). There are plenty of examples of malloc'ing 2-d arrays on here, try searching and see what you find.

>>How can I modify values bit-by-bit.
Bit manipulation is in the FAQ.

>>width = atoi(argv[2]);
If this fails 'cos the user entered a non-number, it will return 0. You'll need to check for that before calling malloc. Better still, use strtol() which allows you to validate the conversion.

[fatinez]

Thanks, I'll see what I can come up with.