void function bubble_sort doesn't sort arrays

Question

A am trying an implementation of some sorting algorithms and I have to calculate how much time they spend. This is the function I wrote:

void bubble_sort(int A[], int len) {
bool ord = false;
    for (int i=0; i<len-1 && ord==false; i++) {
        ord = true;
        for (int j=len-1; j>i; j--) {
            if (A[j]-1>A[j]) {
                ord = false;
                swap(A[j]-1, A[j]);
            }
        }
    }
}

And of course here there is a typical swap() function:

void swap(int x, int y) {
    int d;
    d = x;
    x = y;
    y = d;
}

I am not having troubles with Insertion Sort, Selection Sort and Merge Sort. By the way bubble_sort is not sorting the numbers in my array.

I cannot find what's wrong. Do you have any ideas?

there are several possible fixes, but as said by others, your swap is wrong. — RichardPlunkett
– RichardPlunkett, Commented Jan 12, 2014 at 23:09

score 3 · Accepted Answer · 2014-01-13 01:27:33Z

3

In C, function parameters are passed by value, not by reference. your swap() function does nothing (it doesn't even return... didn't your compiler complain?)

To actually sort, you have to change swap() to

void swap(int *x, int *y) {
    int d = *x;
    *x = *y;
    *y = d;
    return;
}

and invoke it with

swap(&A[j-1], &A[j]);

edited Jan 13, 2014 at 1:27

answered Jan 12, 2014 at 22:57

user3185968

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2 Comments

Alberto Rossi Over a year ago

I use wxDevC++ and it doesn't complain.

this Over a year ago

@EOF Your function is wrong. Read your the firs sentence of your own answer to fix it. Also your don't have to return a void function.

laaposto · Accepted Answer · 2014-01-12 23:00:24Z

1

You have to include -1 in array A. Not outside the []. Your code non just chech if value in A[j]minus 1 is bigger than value in A[j]. Which is obviously always false.

Also in swap function you dont pass the ponter of the Array A. Actually swap() does nothing.

Try

if (A[j-1]>A[j]) {
                ord = false;
              int temp=A[j-1];
           A[j-1]=A[j];
           A[j]=temp;

edited Jan 12, 2014 at 23:00

answered Jan 12, 2014 at 22:53

laaposto

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2 Comments

Alberto Rossi Over a year ago

Your code works, going to accept it. I have also removed the swap function

laaposto Over a year ago

@AlbertoRossi yes you remove swap and also declare int temp outside the loop for a cleaner code

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