Compare arrays of words in C

How I can compare 2d arrays of char in C? I tried this

        Char **arr_1;
        Char **arr_2;

        ...// malloc. Its OK. 

        for (I=0; I<n; I++)
        {
           If (strcmp (arr_1[I],arr_2[I])==0)
                // do smth
        }

But it doesn't work . I'm not good in pointers.

Arrays have some array of words.

Thanks