#include <stdio.h>
#include <direct.h>
#include <string.h>
FILE *fp;
int main(int argc, char *argv[]) {
    int i, n;
    char c, buffer[10][MAXPATH], *p;
    strcpy(buffer[0], argv[0]);
    strcpy(strrchr(buffer[0], '.'), ".DIR");
    if ((fp = fopen(buffer[0], "r")) == NULL) {
        printf("Can't open %s\n", buffer[0]); return 1;
    }
    for(n = 0; n < 10; n++) {
        if (fgets(buffer[n], MAXPATH, fp) == NULL) break;
        if ((p = strchr(buffer[n], '\n')) == NULL) {
            puts("Path too long."); return 1;
        }
        *p = '\0';
    }
    fclose(fp);
    if (argc == 2) {
        i = argv[1][0] - '0';
        if (i >= 0 && i < n) {
            if (chdir(buffer[i])) {
                printf("Unable to change directory. %s\n", buffer[i]); return 1;
            }
            c = buffer[i][0];
            if (c >= 'a' && c <= 'z') c -= 0x20;
            if (buffer[i][1] == ':' && c >= 'A' && c <= 'Z') {
                if (_chdrive(c - 'A' + 1)) {
                    printf("Unable to change drive. %s\n", buffer[i]); return 1;
                }
            }
            return 0;
        }
    }
    for(i = 0; i < n; i++) printf("%2d : %s\n", i, buffer[i]);
    return 0;
}