Need help in understanding what is going on in C program

Question

So I have very weird bug that I cannot understand. I am running loop and checking for NULL value then I suppose to terminate loop. But, I am getting some EXC_BAD_ACCESS issue after I have the following values (as you can see on the screenshot)

This is additional piece of code that returns char string

char *TKGetNextToken(TokenizerT *tk) {

    if((*tk).currentToken)
        return *(*tk).currentToken++;
    else
        return NULL;

}

and actual structure

struct TokenizerT_ {
    char **currentToken;
    char **tokens;
}tokenizer;

And that is what I have for my pointers:

 char **words;
 words = (char **)malloc(sizeof(char*) * numberOfWords);
 for (int i = 0; i < numberOfWords; i++)
 words[i] = (char *)malloc(strlen(ts)+1);

 tokenizer.tokens = words;
 tokenizer.currentToken = words;

I have no idea why this error can occur and why. Because we can have either pointer that points somewhere or NULL value...

Answer 1

Your TKGetNextToken tests for a NULL that is never present. Add a NULL entry at the end:

words = (char **)malloc(sizeof(char*) * (numberOfWords +1));
for (int i = 0; i < numberOfWords; i++)
    words[i] = (char *)malloc(strlen(ts)+1);
words[i] = NULL;