Help understanding bubblesort hw?

Code:

---

#include <stdio.h>
#include <stdlib.h>
  void bubblesort(int a[],int n);
 
  int main()
{
   
    int comp, pass, tmp, n;
    int a[];
    pass = 1;
    while(comp <= n - pass)
    {
        if(a[comp-1] > a[comp])
        {
            tmp = a[comp-1];
            a[comp-1] = a[comp];
            a[comp] = tmp;
        }
        comp = comp + 1;
    }
    pass = pass + 1;
    system("pause");
    return 0; 
}

---

is what i have so far and it tells me that:
array size missing in 'a'

also im having trouble understanding the homework

Write two functions, both accepts two arguments, an integer array: a and an integer: n. The first function outputs the n elements stored

in the array, and the second function sorted the array using the basic bubble sort as provided in the notes with an improvement. The

improvement is based on the following observation. When there is no exchange between any data in a pass of the bubble sort, the sequence

is already sorted in non-decreasing order. As a result, there is no need to continue and hence can terminate the sort. Add an output

statement to show the number of passes that the sorting algorithm has actually taken.

Then write a C program to test your solution. It first requests n, the number of integers to be sorted. Then it input n integers. Then

it calls the output function to output the original sequence of integers, then calls the bubble sort, and finally calls the output

function to output the final sorted sequence.

can anyone explain this more clearly for me?

thank you!

Quote:

---

Originally Posted by beretta

is what i have so far and it tells me that:
array size missing in 'a'

---

hmmm....could there be something obvious you have failed to investigate?!!??!

Code:

---

int a[];

---

well i tried it without that string, and it still gives me the same error sir. the point is that i don't know what size the array will be, im going to have to add to the program an input.

Quote:

---

Originally Posted by beretta

the point is that i don't know what size the array will be.

---

Yep. So pick something, or allocate dynamically with malloc().

well i used 4, then i added

printf("Please enter an integer: ");
scanf("%d", &n);

but when i do that nothing happens =\

Code:

---

#include <stdio.h>
#include <stdlib.h>
 
 
int main()
{
  void bubblesort(int a[],int n);
    int cmp, pass, tmp, n, a[4];
    printf("Please enter an integer: ");
    scanf("%d", &n);
    {
      pass = 1;
      while(cmp <= n)
      {
        cmp = 1;
        while(cmp <= n - pass)
        {
          if(a[cmp-1] > a[cmp])
                        {
                            tmp = a[cmp-1];
                            a[cmp-1] = a[cmp];
                            a[cmp] = tmp;
                        }
          cmp = cmp + 1;
        }
        pass = pass + 1;
      }
    }
    return 0; 
}

---

have that so far. does it look like im in the right direction?

You'll want this part of your code in a loop will you not?

Code:

---

    printf("Please enter an integer: ");
    scanf("%d", &n);

---

May I suggest you use a #define Size 4, and then use a for loop from 0 to < Size to fill the array?

Also, you declared a sort function, but so far, haven't created it, or called it.

explain please?

and i thought n would only be called initially.

i also wasn't instructed or taught on using #define size 4, we have to use it as given =\

Ok, i think i understand what you mean, first i need to set up the sort as in define it. then i can call it in the actual program, so like this?

Code:

---

#include <stdio.h>
#include <stdlib.h>
 
void bubblesort(int a[],int n)
    {
      int cmp, pass, tmp;
      pass = 1;
      while(cmp <= n)
      {
        cmp = 1;
        while(cmp <= n - pass)
        {
          if(a[cmp-1] > a[cmp])
                        {
                            tmp = a[cmp-1];
                            a[cmp-1] = a[cmp];
                            a[cmp] = tmp;
                        }
          cmp = cmp + 1;
        }
        pass = pass + 1;
      }
    }   
int main()
{
   
    int cmp, pass, tmp, n, a[4];
    printf("Please enter an integer: ");
    scanf("%d", &n);   
   

    system("pause");
    return 0; 
}

---

I think this is even a "neater" version, but tell me if i'm wrong.

Code:

---

/*Defining the bubblesort*/
void bubblesort(int a[],int n)
    {
      int cmp, pass, tmp;
      pass = 1;
      while(cmp <= n)
      {
        cmp = 1;
        while(cmp <= n - pass)
        {
          if(a[cmp-1] > a[cmp])
                        {
                            tmp = a[cmp-1];
                            a[cmp-1] = a[cmp];
                            a[cmp] = tmp;
                        }
          cmp = cmp + 1;
        }
        pass = pass + 1;
      }
    }   

/* The actual method of sorting */
#include <stdio.h>
#include <stdlib.h>

void bubblesort(int a[],int n);

int main()
{
    int a[100];
    int cmp, pass, tmp, n;
    printf("Please enter an integer: ");
    scanf("%d", &n);
   
   
    system("pause");
    return 0; 
}

---

Code:

---

      int cmp, pass, tmp;
      pass = 1;
      while(cmp <= n)

---

Look at these 3 lines of code. On the third line, you are checking if cmp is less than or equal to n. You have never assigned any value to cmp though.

yes i did, its 1

No you didn't. Look again.

cmp = 1;
while(cmp <= n - pass)

I'm talking about the code I posted.

*slaps head* i look in wrong area, i understand what you are saying

ok now how do i call bubblesort into my actual program?

No. Code is executed line by line, in order. In other words if I have:

Code:

---

int i;
if(i == 5)
    printf("i is equal to 5\n");
i = 5;

---

In the above code, the check if i is equal to five happens before i is set to 5.

yea i understand, i apologize about that.

so if i added cmp = 1;

does the sort look valid?

if so how do i actually use it in the program

Your code is still wrong. The bubblesort() function will never return; it will loop forever. Look at your loop conditions. The outer loop will run forever because cmp will always be less than or equal to n.

As for how to use your program, here is one method:

Code:

---

int main(void)
{
    int a[3] = { 3, 2, 1 };
    bubblesort(a, sizeof(a) / sizeof(int));
    return 0;
}

---

hmm, i'm a bit lost honestly.

Here is your code with a few changes to the main function so it will run:

Code:

---

#include <stdio.h>
#include <stdlib.h>

void bubblesort(int a[],int n)
{
    int cmp = 1, pass, tmp;
    pass = 1;
    while(cmp <= n)
    {
        printf("Inside outer loop.  cmp=%d, n=%d\n",cmp,n);
        cmp = 1;
        while(cmp <= n - pass)
        {
            printf("Inside inner loop.  cmp=%d, n-pass=%d\n",cmp,n-pass);
            if(a[cmp-1] > a[cmp])
            {
                printf("Swapping variables\n");
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
            }
            cmp = cmp + 1;
        }
        pass = pass + 1;
    }
}

int main(void)
{
    int a[3] = { 3, 2, 1 };
    bubblesort(a, sizeof(a) / sizeof(int));
    return 0;
}

---

Now compile and run that code. What happens?

I liked where you where with this code, Baretta. I've taken the liberty of just re-arranging it so it's "right side up" (has the includes at the top of the program).

Code:

---

#include <stdio.h>
#include <stdlib.h>

void bubblesort(int a[],int n);

int main()
{
    int a[10] = { 3, 1, 7, 6, 2, 8, 9, 5, 4, 0 };
    int cmp, pass, tmp, n; //we can remove this line of code, since it belongs in the bubblesort() function.
                //printf("Please enter an integer: ");
                //scanf("%d", &n);
   
   
    system("pause");
    return 0; 
}



/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
  int cmp, pass, tmp;
     

  pass = cmp = 0;      <-- We haven't made any passes or comparisons, yet
      while(cmp < n)    <-- Just less than n, not equal to, this is C
      {
        cmp = 1;            <- instead of =1, let's increment it by one: cmp++;
        while(cmp <= n - pass)  <-- looks correct
        {
          if(a[cmp-1] > a[cmp])
          {
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
          }
          cmp = cmp + 1;
      }
      pass = pass + 1;
  }
}   

/* The actual method of sorting */

---

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int a[4];
    int n;
    printf("Please enter an integer: ");
    scanf("%d", &n);
    bubblesort(a, sizeof(a) / sizeof(int));
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
      int cmp, pass, tmp;
      pass = 1;
      cmp = 1;
      while(cmp <= n)
      {
        cmp = 1;
        while(cmp <= n - pass)
        {
          if(a[cmp-1] > a[cmp])
                        {
                            tmp = a[cmp-1];
                            a[cmp-1] = a[cmp];
                            a[cmp] = tmp;
                        }
          cmp = cmp + 1;
        }
        pass = pass + 1;
      }
}

---

thank you for the arrangement help
does that look any better?

it compiles and i can enter n, but it does nothing afterwards

hmm i see i forgot the add an output that would state the array. hmm

It's hard to believe, but when you are designing a program, in the first half of the design process, ignore the damn details.

Whether the program works is at this time, a mere detail. Welcome to top-down design! :)

Did you make the other changes in the code as I marked them out, previously?

*bithub: It's after Midnight, and you're asking a young person to waste sleep to prove that his code will loop endlessly, as you stated.

That seems unnecessary at the very least, at this hour.

Quote:

---

does that look any better?

---

It looks better, but your indentation still needs some help. Look at the code I posted; it is properly indented.

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int a[4];
    int n;
    printf("Please enter an integer: ");
    scanf("%d", &n);
    bubblesort(a, sizeof(a) / sizeof(int));
   
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    int cmp, pass, tmp;
    pass = 1;
    cmp = 1;
    printf("Inside outer loop.  cmp=%d, n=%d\n",cmp,n);
    while(cmp <= n - pass)
    {
        printf("Inside inner loop.  cmp=%d, n-pass=%d\n",cmp,n-pass);
        if(a[cmp-1] > a[cmp])
        {
            tmp = a[cmp-1];
            a[cmp-1] = a[cmp];
            a[cmp] = tmp;
        }
        cmp = cmp + 1;
    }
    pass = pass + 1; 
}

---

it's working and I fixed the indentions for you sir =)

Quote:

---

it's working!

---

No it's not. Your code isn't sorting anything. Bubble sorts require 2 loops, you just have one now...

well i meant that some code is actually showing. lol.

hmmmmmm

You still have a problem in your main function. You are not assigning any values to the array you are sorting. Put some values in there!

Code:

---

int main(void)
{
    int i;
    int a[4] = {4, 8, 2, 1};
    printf("Before calling bubblesort()...\n");
    for(i = 0; i < sizeof(a) / sizeof(a[0]); ++i)
        printf("%d ", a[i]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    printf("After calling bubblesort()...\n");
    for(i = 0; i < sizeof(a) / sizeof(a[0]); ++i)
        printf("%d ", a[i]);
    printf("\n");
    system("pause");
    return 0; 
}

---

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int a[10];
    bubblesort(a, sizeof(a) / sizeof(int));
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    printf("Please enter an integer: ");
    scanf("%d", &n);
    int cmp, pass, tmp;
    pass = 1;
    cmp = 1;
    while(cmp <= n)
    {
        printf("Inside inner loop.  cmp=%d, n-pass=%d\n",cmp,n-pass);
        if(a[cmp-1] > a[cmp])
        {
            tmp = a[cmp-1];
            a[cmp-1] = a[cmp];
            a[cmp] = tmp;
        }
        cmp = cmp + 1;
        pass = pass + 1;
    }   
}

---

that seems to work better

bithub, we do not use the for function in our class

That code is just to help you see what is going on with your program. Anyways, the same thing can be implemented with a while loop.

Code:

---

int main(void)
{
    int i = 0;
    int a[4] = {4, 8, 2, 1};
    printf("Before calling bubblesort()...\n");
    while(i < sizeof(a) / sizeof(a[0])
        printf("%d ", a[i++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    ...
}

---

just mentioning it to you sir, I understand what you are saying though. thank you.

hmm im not understanding how to view after.

Only while loops, eh? :)

How about something like

Code:

---

while( i < n)
  print a[i]

---

This is NOT code, just pseudo-code.

i got that, now i need to run a loop to where it finishes the sort

Yeah, I had to make some changes to get this version to sort. I'm not sure it's everything your teacher wants, however.

Code:

---

#include <stdio.h>
#include <stdlib.h>

void bubblesort(int a[],int n);
void showIt(int a[], int n);

int main()
{
    int a[10] = { 3, 1, 7, 6, 2, 8, 9, 5, 4, 0 };
    int n = 10;

    bubblesort(a, n);
    showIt(a, n);
    printf("\n\n\t\t\t    press enter when ready");
    n = getchar();
    return 0; 
}

/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
  int cmp, pass, tmp, swapped;

  pass = cmp = 0; 
  swapped = 1;
  while(swapped)
  {
      swapped = 0;
      cmp = 1;         
      while(cmp < n - pass) 
      {
        if(a[cmp-1] > a[cmp])
        {
            swapped = 1;
            tmp = a[cmp-1];
            a[cmp-1] = a[cmp];
            a[cmp] = tmp;
        }
        cmp++;
      }
      pass++;
  }
  printf("\n Our Sort had %d comparisons, and %d passes", cmp, pass);
}   
void showIt(int a[], int n)  {
  int i;
  printf("\n\n\n");

  for(i = 0; i < n; i++)
    printf("%d ", a[i]);
}

---

I don't like the cmp being reset to 1, but it appears part and parcel of this version of the bubblesort.

hmmm

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int list = 0;
    int a[4] = { 4, 8, 2, 1};
    printf("Before: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    list = 0;
    printf("After: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    printf("Please enter an integer: ");
    scanf("%d", &n);
    int cmp, pass, tmp;
    pass = 1;
    cmp = 1;
    while(cmp <= n)
    {
        printf("Inside inner loop.  cmp=%d, n-pass=%d\n",cmp,n-pass);
        if(a[cmp-1] > a[cmp])
        {
            tmp = a[cmp-1];
            a[cmp-1] = a[cmp];
            a[cmp] = tmp;
        }
        cmp++;
        pass++;
    }   
}

---

this is what i have so far.

The output is in sorted order, and all array values are present.

I am receiving no warning or errors, of any kind, and have run this numerous times.

What's not working?

As bithub noted, you must have two nested loops to run a bubblesort. (actually, any sort I ever heard of).

You only have 1.

You can either keep the one loop, and have it not sort, or add another loop to it, and have it sort.

so your showit is your second loop?

No, showIt just prints out the array, it sorts nothing.

Look in bubblesort(), and see the two while loops, nested inside each other?

That's what's doing the sorting.

how would i loop with

Code:

---

printf("Please enter an integer: ");
    scanf("%d", &n);
    int cmp, pass, tmp, swch;
    pass = 1;
    cmp = 1;
    swch = 0;
    while(swch)
    {
        swch = 1;
        cmp = 0;
        while(cmp < n - pass)
        {
            if(a[cmp-1] > a[cmp])
            {
                swch = 0;
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
            }
            cmp++;
        }   
        pass++;
    }

---

cause that does nothing.

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int list = 0;
    int a[4] = { 4, 8, 2, 1};
    printf("Before: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    list = 0;
    printf("After: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    printf("Please enter an integer: ");
    scanf("%d", &n);
    int cmp, pass, tmp, swch;
    pass = 0;
    cmp = 0;
    swch = 1;
    while(swch)
    {
        swch = 0;
        cmp = 1;
        while(cmp < n - pass)
        {
            if(a[cmp-1] > a[cmp])
            {
                swch = 1;
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
            }
            cmp++;
        }   
        pass++;
    }   
    printf("Our Sort had %d comparisons, and %d passes\n", cmp, pass);
}

---

this works. now i need it to stop when it is finished sorting.

When swch stays with a value of zero, then the sorting will stop.

that doesn't work cause i can type in 6 and get a negative number sir

[edit] WHOOPS! I just noticed there's 4 pages here, not 2! (I though the last post was hours ago)...anyway you might find this handy:

Quote:

---

Originally Posted by your prof

...an improvement. The improvement is based on the following observation. When there is no exchange between any data in a pass of the bubble sort, the sequence
is already sorted in non-decreasing order. As a result, there is no need to continue and hence can terminate the sort.

---

That's a modified bubblesort; it uses a flag:

Code:

---

#include "stdio.h"

void bubblesort (int *ray, int len) {
        int i, flag=0, tmp;
        while (flag==0) {
                for (i=0;i<len-1;i++) {  /* loop thru all the elements, first to SECOND last */
                        if (ray[i]>ray[i+1]) {        /* (since we must compare to the next element) */
                                tmp=ray[i+1];
                                ray[i+1]=ray[i];
                                ray[i]=tmp;
                                flag++;    /* a change made, flag goes up */
                        } 
                } 
                if (flag==0) break;    /* no changes made! while loop is finished */
                flag=0; /* reset flag */
        } 
}

int main () {
        int ray[11]={666,10,6,34,5,16,102,45,7,9,1}, i;
        bubblesort(ray,11);
                /* verify */
        for (i=0;i<11;i++) printf("%d\n",ray[i]);
        return 0;
}

---

You're going to tell me what negative number you're talking about, right?

I was worried about your sleep after Midnight, now I'm worried about mine! :)

i've never heard of a flag, my teacher is an idiot.

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int list = 0;
    int a[4] = { 4, 8, 2, 1};
    printf("Before: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    list = 0;
    printf("After: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    printf("Please enter an integer: ");
    scanf("%d", &n);
    int cmp, pass, tmp, swch;
    pass = 0;
    cmp = 0;
    swch = 1;
    while(swch)
    {
        swch = 0;
        cmp = 1;
        while(cmp < n - pass)
        {
            if(a[cmp-1] > a[cmp])
            {
                swch = 1;
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
            }
            cmp++;
        }   
        pass++;
    }   
    printf("Our Sort had %d comparisons, and %d passes\n", cmp, pass);
}

---

if i use that code and type in the number 6
i get the answer of -1124

Quote:

---

Originally Posted by beretta

i've never heard of a flag, my teacher is an idiot.

---

Yeah, sorry -- I honestly didn't notice the rest of the thread and thought you'd gotten stuck. Don't get too distracted by my little contribution ;)

The reason you're not using a flag is you're not using two loops in the function, you're using a control loop for the function, which should accomplish the same thing, so that's okay. Lemme take a look at your last post...

yea, and honestly im not even sure if i should be using:
while(list < sizeof(a) / sizeof(a[0])) or bubblesort(a, sizeof(a) / sizeof(int));

meaning the sizeof parts

You don't need sizeof, anything.

If you were malloc'ing your own memory dynamically, then you would need sizeof().

Looks mostly fine to me...

Quote:

---

Originally Posted by beretta

yea, and honestly im not even sure if i should be using:
while(list < sizeof(a) / sizeof(a[0])) or bubblesort(a, sizeof(a) / sizeof(int));
meaning the sizeof parts

---

Well, you are suppose to be inputing all the data anyway, so that will determine the number you are calculating now with sizeof.

The bubblesort is done, now you just have to organize the rest of it. Move this into main:

Code:

---

printf("Please enter an integer: ");
scanf("%d", &n);

---

The last place that should be is in the sort function. You want to get all the user input *before* anything else happens.

Then just turn your while/printf loop

Code:

---

while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);

---

into an actual function, as per the prof's specs.

w/r/t the user input have you/are you supposed to use malloc() to create a dynamically sized array?

ps. you are using a flag -- you call it "swch". I thought of it that way too (as something that's switched on as a signal). The term "flag" prevents confusion with the "switch/case" construct which is used in C and most other languages.

MK, how is sizeof() going to help sort an array of 100 elements, which might hold only 20 numbers in it?

Since it's not dynamically allocated, why emphasize sizeof(), when sizeof() won't help in the above case, which is common?

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int n;
    int list = 0;
    int a[4] = { 4, 8, 2, 1};
    printf("Please enter an integer: ");
    scanf("%d", &n);
    printf("Before: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    list = 0;
    printf("After: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    system("pause");
    return 0; 
}



/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    int cmp, pass, tmp, end;
    pass = 1;
   
    while(pass <= n-1)
    {
      cmp = 0;
      end = n - 1 - pass;
        while(cmp <= end)
        {
            if(a[cmp] > a[cmp+1])
            {
               
                tmp = a[cmp];
                a[cmp] = a[cmp+1];
                a[cmp+1] = tmp;
                cmp++;
            }
          pass++;
        }   
       
    }   
    printf("Our Sort had %d comparisons, and %d passes\n", cmp, pass);
}

---

what about this version. can you fix this one?

No. It makes no sense in main().

sizeof(a) / sizeof(a[0]) will not tell you how many elements are being used in the array, so it's no good for this.

how can you make sense of it?

I think the sizeof issue is a red herring at this point.

Here's a way to input the data. If you aren't using malloc(), then you need to set the array bigger than the user could possibly want it; n will act as a control with the functions, so the extra elements won't be involved.

Code:

---


#include <stdio.h>
#include <stdlib.h>

void showarray (int *rayptr, int len) {
        int i=0;
        while (i<len) {
                printf("%d ",rayptr[i]);
                i++;
        }
        printf("\n");
}

int main() {
        int n, a[100], i=0; /* presume we won't need more than one hundred numbers */
        printf("Enter an array size: ");
        scanf("%d",&n);
        printf("Enter %d numbers seperated by spaces: ",n);
        while (i<n) {
                scanf("%d",&a[i]);
                i++;
        } 
                /* verify using a showarray function */
        showarray(a,n);
        return 0;
}

---

Just combine that with your bubblesort. This does not verify the input -- it presumes the user is able to properly enter the numbers.

didn't work for me

Quote:

---

Originally Posted by beretta

didn't work for me

---

That post??? I tested it. What seems wrong?

set n = sizeof(a) / sizeof(a[0] if you want to use sizeof().

It stinks though, because you may (and frequently will), make your array larger than you need, and just use part of it for your data.

Then sizeof() just sucks eggs, and you'll need n (some variable), to tell your program how many numbers, or strings or whatever, you need to have sorted, in your array. Sizeof() can never do that.


OK, off my soapbox, down to business:

1) If you're going to have the user input the values into a[], then remove the numbers now being put into a, by the program, at initialization.

2) set n to *something* that you want, that tells bubblesort what size the array is (or what number of elements it needs to sort).

3)Put the user input inside a while loop.

I've got to hit the sack for some zzzz's.

Good luck, Baretta.

Quote:

---

Originally Posted by Adak

I've got to hit the sack for some zzzz's.

---

Good idea Adak, you usually seem more lucid than this ;)

=( )

Code:

---

#include <stdio.h>
#include <stdlib.h>

/* The actual method of sorting */

void bubblesort(int a[],int n);

int main()
{
    int n;
    int list = 0;
    int a[10] = { 4, 8, 2, 1, 6, 5, 3, 9, 8, 1};
    printf("Please enter an integer: ");
    scanf("%d", &n);
    printf("Before: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    bubblesort(a, sizeof(a) / sizeof(int));
    list = 0;
    printf("After: ");
    while(list < sizeof(a) / sizeof(a[0]))
        printf("%d", a[list++]);
    printf("\n");
    system("pause");
    return 0; 
}


/*Defining the bubblesort*/
void bubblesort(int a[],int n)
{
    int cmp, pass, tmp, swch;
    pass = 0;
    cmp = 0;
    swch = 1;
    while(swch)
    {
        swch = 0;
        cmp = 1;
        while(cmp < n - pass)
        {
            if(a[cmp-1] > a[cmp])
            {
                swch = 1;
                tmp = a[cmp-1];
                a[cmp-1] = a[cmp];
                a[cmp] = tmp;
            }
            cmp++;
        }   
        pass++;
    }   
    printf("Our Sort had %d comparisons, and %d passes\n", cmp, pass);
}

---

ok apparently i am suppose to make the n a variable that hte user types in:
- program asks for n
-then you type in the numbers you would like to sort

so if n = 6 there will be six numbers to sort.

any ideas, ill reply when i get back from work

Quote:

---

Originally Posted by beretta

ok apparently i am suppose to make the n a variable that hte user types in:
- program asks for n
-then you type in the numbers you would like to sort

---

That is exactly what I was showing you in post #58! You do not have to do it that way, of course.

Yea i understand what you are saying, i'm workin on it right now

Code:

---

#include <stdio.h>
#include <stdlib.h>

int BubbleSort(int info, int next);//returns the lesser of the 2.

void main(void)
{

int *ptr = malloc(10 * sizeof (int));// will hold entire input array
int next=0;int info;

int i;

for (i=0;i<<*ptr;i++)
{
       
        printf("Enter Number Please:");
        scanf("%i",&info);
        if (info<=next)
        {
                *ptr=info;
               
        }
        else *ptr=BubbleSort(info,next);
        printf("%i, ",*ptr);
        ptr++;
}
}
int BubbleSort(int info, int next)
{
        int tempInfo;
        tempInfo=info;
        info=next;
        next=tempInfo;
        return info;
}

---

only I haven't figured out why nothing is being output by the printf("%i, ", *ptr);

Am I close?


- Edward