I had a feeling that it was gonna be something stupid. I didn't notice the lack of braces. I guess that's why all my professors have always said not to be lazy and leave out the braces when there is only one statement. Thank you so much. I added the two braces and I finally got it to work. I thought something was wrong with my logic so I brought my dry-erase board and drew the little processes and the pipes and everything and couldn't figure out what was going wrong. Thanks again.

baavgai, on 05 November 2012 - 02:31 PM, said:

Anyone who doesn't program in C or Assembly has it easy!

I'm learning both right now and I miss the old days of Java. Anything that involves arrays--and strings by extension--makes me wanna pull my hair out. But it's nice to learn a language you can do so much with.

jimblumberg, on 05 November 2012 - 07:35 AM, said:

Wow, that's really good to know. I'll definitely keep that in mind from now on. I'm learning C in my class called "Advanced Programming," after programming in C for about two months I can see where the "Advanced" comes from. C makes me appreciate OOP that much more, but there's something enticing about C

Ok, I'm sorry for the ambiguous "proper results," but I was in a bit of a rush when I posted the question.

Thanks for the insight, I learned to program in Java where + concatenated two strings, and I completely forgot about how strings are handled in C. I always able to fix the problem by using strcat in lieu of '+' and using another method substring that modifies strncpy a bit. For the sake of education, here's the code in case anyone else has a similar problem.

void permute(char* prefix, char* post) {
   if (strlen(post) == 0)
        printf("%s\n", prefix);
    else {
        char* letters = getChar(*post);
        for (int i = 0; i < strlen(letters); i++) {

            //strings needed for recursive premute call
            char *combined = calloc(sizeof(char), 50);
            char *prefix_new = substring(letters, i, 1);
            char *postfix_new = substring(post, 1, strlen(post));

            //combines the strings
            strcat(combined, prefix);
            strcat(combined, prefix_new);
            
            permute(combined, postfix_new);

            //frees allocated memory
            free(combined);
            free(prefix_new);
            free(postfix_new);
        }
        free(letters);
    }
}

Here's the substring method

char *substring(char *s, int start, int end) {
    char *result = calloc(sizeof(char), 50);
    return strncpy(result, s + start, end);
}

I'm pretty sure it may not be the most elegant solution, but here are the results

AD
AE
AF
BD
BE
BF
CD
CE
CF

which are the wanted results, plus no memory leaks--which is always good.

Thanks for the help

Did you try compiling the code? When I compile it I get errors...