Euler 8

euler8.c

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

void readfile(char *file, int *buffer, int size, int *read) {
    FILE *f = fopen(file, "r");
    char c;
    int pos;
    while ( (c = getc(f)) != EOF && pos < size - 1) {
        if (c >= '0' && c <= '9')
            buffer[pos++] = c - '0';
    }
    *read = pos;
    fclose(f);
}

int main(int argc, char **argv) {
    int buffer[10000];
    int read;
    readfile("e8.txt", buffer, 10000, &read);

    int i;
    int largest = 1, p;
    for (i = 0; i < read - 5; ++i) {
        p = buffer[i] * buffer[i + 1] * buffer[i + 2] * buffer[i + 3] * buffer[i + 4];
        if (p > largest)
            largest = p;
    }
    printf("%d\n", largest);
    return 0;
}