Read more images at once

Hi all. How can I read multiple images from a folder, then process them(add some effects) and then redirect them to a specific folder, with a specific name?

Code:

---


    char input[] = "./input/images/file1.bmp";   
    char output[] = "./output/newfile1.bmp";
    FILE *fIn = fopen(input, "rb");
    FILE *fOut = fopen(output, "wb");
    if (!fIn || !fOut)
    {
        printf("File error.\n");
    }

---

this is only part of the code. How can I process multiple images at once? From my example, only one image is processed.
A little help please?

Accessing command line parameters/arguments
So for example, you could type
myprog ./input/images/*.bmp ./output

Or you could just specify the names of your input and output directories, and use this.
Accessing a directory and all the files within it