Thread: Array pointer as function argument?

  1. #1
    Registered User
    Join Date
    Sep 2011

    Array pointer as function argument?


    I have been asked to implement a method

    void word_not(lc3_word_t *R, lc3_word_t *A)
    which, as you can see, takes 2 pointers to a array of BITS, defined as follows:
    typedef enum {
        ZERO = (uint8_t) 0, ONE = (uint8_t) 1
    } BIT;
    typedef BIT lc3_word_t[16];
    The main method invokes the function:

    word_not(&result, &a_value)
    which passes the address of two lc_word_t types to word_not. The function is supposed to negate each bit in a_value (NOT function) and write it into the corresponding bit in result.

    What should I put in the body of word_not to accomplish this? I begin by looping from 0 to 15 (a total of 16 times, the length of the word type), but I am not sure how to check & store elements in arrays when I am given only pointers (addresses?) to the arrays. I am very confused what the data fields for the pointer arugments look like when addresses are passed into them.

    I have tried different things like making BIT pointers (BIT *) but when I print the contents of result it always appears to have addresses instead of BITs. What should I do?

  2. #2
    Registered User
    Join Date
    May 2011
    Around 8.3 light-minutes from the Sun
    Quote Originally Posted by mtn_student View Post
    ... What should I do?
    I would suggest you learn about pointers. Specifically, pointers to pointers. Take a look at Prelude's Pointer Tutorial.
    Quote Originally Posted by anduril462 View Post
    Now, please, for the love of all things good and holy, think about what you're doing! Don't just run around willy-nilly, coding like a drunk two-year-old....
    Quote Originally Posted by quzah View Post
    ..... Just don't be surprised when I say you aren't using standard C anymore, and as such,are off in your own little universe that I will completely disregard.
    Warning: Some or all of my posted code may be non-standard and as such should not be used and in no case looked at.

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