Returning string from C function

Either allocate the string on the stack on the caller side and pass it to your function:

void getStr(char *wordd, int length) {
    ...
}

int main(void) {
    char wordd[10 + 1];
    getStr(wordd, sizeof(wordd) - 1);
    ...
}

Or make the string static in getStr:

char *getStr(void) {
    static char wordd[10 + 1];
    ...
    return wordd;
}

Or allocate the string on the heap:

char *getStr(int length) {
    char *wordd = malloc(length + 1);
    ...
    return wordd;
}

char word[length];
char *rtnPtr = word;
...
return rtnPtr;

This is not good. You are returning a pointer to an automatic (scoped) variable, which will be destroyed when the function returns. The pointer will be left pointing at a destroyed variable, which will almost certainly produce "strange" results (undefined behaviour).

You should be allocating the string with malloc (e.g. char *rtnPtr = malloc(length)), then freeing it later in main.

You are allocating your string on the stack, and then returning a pointer to it. When your function returns, any stack allocations become invalid; the pointer now points to a region on the stack that is likely to be overwritten the next time a function is called.

In order to do what you're trying to do, you need to do one of the following:

1. Allocate memory on the heap using malloc or similar, then return that pointer. The caller will then need to call free when it is done with the memory.
2. Allocate the string on the stack in the calling function (the one that will be using the string), and pass a pointer in to the function to put the string into. During the entire call to the calling function, data on its stack is valid; its only once you return that stack allocated space becomes used by something else.