a hex dumper in C.. what do you think?

Here's the code tell me what you think

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define HEXFILE "hex.txt"
#define NONPRINTCHAR '.'
#define HEXNUM 8

int checksc(int c) {
    if(c == '\n' || c == '\r' || !isprint(c))
    return NONPRINTCHAR;
    return c;
}
int main(int argc, char **argv) {
   
    FILE *fp, *fp2;
    char buffer[HEXNUM + 2];
    int i = 0;
    int c;
    /* checking for arguments */
    if(argc == 1 || argc > 3) {
        fprintf(stderr, "%s -[option] file\n", argv[0]);
        return 1;
    }
    /* opening files and error checking */
    if(!(fp = fopen(argv[argc-1], "rb"))) {
            fprintf(stderr, "ERROR: unable to open %s for reading.\n", argv[1]);
            return 2;
    }
    if(!(fp2 = fopen(HEXFILE, "w"))) {
            fprintf(stderr, "ERROR: unable to open %s for writting.\n", HEXFILE);
            fclose(fp);
            return 3;
    }
    fprintf(fp2, "---- hex dump of %s ----\n\n", argv[argc-1]);
    memset(buffer, 0, HEXNUM + 2);
        while((c = fgetc(fp)) != EOF) {
            if(argc == 3) buffer[i] = (char)checksc(c);
            ++i;
            i%=HEXNUM;
            fprintf(fp2, "0x%x", c); // i would use %#x but it doens't work with 0.
            if(i) fputc(' ', fp2);
                else {
                    if(argc == 2) fputc('\n', fp2);
                    else if(argc == 3)
                            fprintf(fp2, "\t\t%s\n", buffer);
                    continue;
                    }
            if(c < 16) fputc(' ', fp2);
        }
    if(i) {
        buffer[i] = 0;
        fprintf(fp2, "\t\t%s\n", buffer);
    }
    fprintf(fp2, "\n\n---- EOF ----");
    fclose(fp);
    fclose(fp2);
    return 0;
}

>>23
Not at all, my Haskell implementation is lazy, meaning that the code will not be run if you do not run the main procedure.

Also, the code is much more legible and logical.