Sally wants more privacy. She decides to create her own branch.

lottery sally$ ls
branches    tags        trunk

lottery sally$ svn copy trunk branches/no_boys_allowed
A         branches/no_boys_allowed

lottery sally$ svn st
?       trunk/pb
A  +    branches/no_boys_allowed
?       branches/no_boys_allowed/pb

lottery sally$ svn commit -m "a private branch so I can work without harry"
Adding         branches/no_boys_allowed

Committed revision 14.

Subversion uses directory branches—a branch shows up in the tree as a directory. DVCS tools use a very different branching model. Some people find directory branches easier because they’re more visible. One problem with directory branches is that it is possible to commit to two branches at the same time.

Now that Sally is working in her own branch, she feels much more productive. She adds support for the “favorite” option. When a user is playing his favorite numbers, his chances of winning should be doubled. In doing this, she had to rework the way command-line args are parsed. And she removes an atoi() call she missed last time. And she restructures all the error checking into one place.

So main() now looks like this:

int main(int argc, char** argv)
{
    int balls[6];
    int count_balls = 0;
    int favorite = 0;

    for (int i=1; i<argc; i++)
    {
        const char* arg = argv[i];

        if ('-' == arg[0])
        {
            if (0 == strcmp(arg, "-favorite"))
            {
                favorite = 1;
            }
            else
            {
                goto usage_error;
            }
        }
        else
        {
            char* endptr = NULL;
            long val = strtol(arg, &endptr, 10);
            if (*endptr)
            {
                goto usage_error;
            }
            balls[count_balls++] = (int) val;
        }
    }

    if (6 != count_balls)
    {
        goto usage_error;
    }

    int power_ball = balls[5];

    int result = calculate_result(balls, power_ball);

    if (result < 0)
    {
        goto usage_error;
    }

    if (LUCKY_NUMBER == power_ball)
    {
        result = result * 2;
    }

    if (favorite)
    {
        result = result * 2;
    }

    printf("%d percent chance of winning\n", result);

    return 0;

usage_error:
    fprintf(stderr, "Usage: %s [-favorite] (5 white balls) power_ball\n", argv[0]);
    return -1;
}

She commits her changes, knowing that the commit will succeed because she is working in her private branch.

no_boys_allowed sally$ svn commit -m "add -favorite and cleanup some other stuff"
Sending        no_boys_allowed/pb.c
Transmitting file data .
Committed revision 15.

I am happy for Sally and her burst of productivity here, but she probably should have made these changes in two or three separate commits instead of squashing them all into one.