Last Time with this Program ... I swear!

This is a discussion on Last Time with this Program ... I swear! within the C Programming forums, part of the General Programming Boards category; Anyone?...

  1. #16
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    Anyone?

  2. #17
    CSharpener vart's Avatar
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    Quote Originally Posted by DonFord81 View Post
    Anyone?
    be patient

    1. to zero arrays at the beginning enough to write

    Code:
    	char matrix_array[DIM][BITNSLOTS(DIM)] ={0};
    	char U_array[BITNSLOTS(UPPER)] ={0};
    	int combination[LOWER]={0};
    No need to call memset

    2.
    Code:
    #define BITMASK(b) (1 << ((b) % CHAR_BIT))
    What bit do you want to set when b == 1?

    3. test_all_zero instead of doing what its name suggests - checks only the

    Code:
    if (BITTEST(bitarray, 0))
    		{
    			return 0;
    		}
    		else
    		{
    			return 1;
    		}
    I could not compile and debug your program because some function is missing.

    Do you pay attention to the compiler warnings?
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  3. #18
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    The function that's probably missing for you is <combination.h>, which is not standard in the C library. I can include the code snippet I used for it, since I found it on an internet forum for such things.

    I changed the test_all_zero code per your suggestion.

    Code:
    int test_all_zero(char* bitarray, int n){
        int i;
        int counter = 0;
        for (i=0; i<n; i++){
            if (!BITTEST(bitarray, i)){
               counter++;
               }
            }
        if (counter == n){
           return (1);
           }
        else{
             return (0);
             }
    }
    And here's the <combination.h> header file:
    Code:
    /*
    	next_comb(int comb[], int k, int n)
    		Generates the next combination of n elements as k after comb
    
    	comb => the previous combination ( use (0, 1, 2, ..., k) for first)
    	k => the size of the subsets to generate
    	n => the size of the original set
    
    	Returns: 1 if a valid combination was found
    		0, otherwise
    */
    int next_comb(int comb[], int k, int n) {
    	int i = k - 1;
    	++comb[i];
    	while ((i >= 0) && (comb[i] >= n - k + 1 + i)) {
    		--i;
    		++comb[i];
    	}
    
    	if (comb[0] > n - k) /* Combination (n-k, n-k+1, ..., n) reached */
    		return 0; /* No more combinations can be generated */
    
    	/* comb now looks like (..., x, n, n, n, ..., n).
    	Turn it into (..., x, x + 1, x + 2, ...) */
    	for (i = i + 1; i < k; ++i)
    		comb[i] = comb[i - 1] + 1;
    
    	return 1;
    }
    However, for DIM = 5 and LOWER = 3, I'm still getting an incorrect answer.

    I can't figure out if my for/while loops are even engaging, since it seems that my program block is just getting skipped. Is that what's happening?

  4. #19
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    I still don't know what the program is doing wrong. I thought it might be something along the lines of having forgotten to run "make_matrix" after every instance of changing U_array, but I've checked the code, and I do run "make_matrix" after every change in U_array, so that's not the problem.

    Can anyone please help me?

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