A hastily thrown together c program to scrape urls out of files in a directory. I don't write c so feel free to laugh (or cry) at all the things I did wrong.

urlscraper.c

#include <stdio.h>
#include <unistd.h>
#include <ftw.h>

#define BUFFER_SIZE (1 * 1024 * 1024)

void filterfile(const char *filepath) {

    unsigned char buffer[BUFFER_SIZE];
    FILE * file;
    char ch;
    int sec;
    int index = -1;
    int x;
    size_t readChars;

    // Try opening the file
    file = fopen(filepath, "rb");
    if (file) {
        do {
            // read from the file
            readChars = fread(buffer, sizeof(unsigned char), BUFFER_SIZE, file);

            // for each char
            for(x = 0; x < readChars; ++x) {

            ch = buffer[x];

        if(index == -1 && ch == 'h') {
            index += 1;
        }
        else if(index == 0 && ch == 't') {
            index += 1;
        }
        else if(index == 1 && ch == 't') {
            index += 1;
        }
        else if(index == 2 && ch == 'p') {
            index += 1;
        }
        else if(index == 3 && ch == 's') {
            sec = 1;
        }
        else if(index == 3 && ch == ':') {
            index += 1;
        }
        else if(index == 4 && ch == '/') {
            index += 1;
        }
        else if(index == 5 && ch == '/') {
            putchar('h');
            putchar('t');
            putchar('t');
            putchar('p');
            if(sec = 1) {
                putchar('s');
                sec = 0;
            }
            putchar(':');
            putchar('/');
            putchar('/');
            index += 1;
        }
        else if(index == 6)
            if ((ch > 34 && ch < 39) || (ch > 39 && ch < 60) || ch == 61 || (ch > 62 && ch < 127)) {
                putchar(ch);
            }
            else {
                putchar('\n');
                index = -1;
            }
        else {
            index = -1;
        }

            }
        } while (readChars == BUFFER_SIZE);

        // close the file
        fclose(file);
    }
    else {
        // Todo: log to stderr
    }
}

int print_entry(const char *filepath, const struct stat *info,
        const int typeflag, struct FTW *pathinfo)
{
    if (typeflag == FTW_F) {
        filterfile(filepath);
    }
    return 0;
}

int main(int argc, char *argv[]) {
    if(argc == 2) {
        return nftw(argv[1], print_entry, 15, FTW_PHYS);
    }
    else {
        printf("Scrapes urls from files in a directory.\n");
        printf("Usage: %s <directory>\n", argv[0]);
        return 0;
    }
}

For reference: the goal was to be faster than grep. At a 5x speed improvement I think this more than qualifies.