Program to combine two arrays into one without repetition of elements and printing the combined array but its not printing

Question

1.00/5 (2 votes)

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C++

#include<stdio.h>
#include<stdlib.h>
int *add(int *p,int a,int *q,int b);

void sort(int *p,int a);
int tem=0;  /* tem is the count of the total elements without repetition*/
int main()
{
    int *p,*q,a,b,i,*r;
    printf("enter the number of elements in the first array\n");
    scanf("%d",&a);
    p=(int *) malloc(a*sizeof(int));

    printf("enter the number of elements in the second array\n");
    scanf("%d",&b);
    q=(int *) malloc(b*sizeof(int));
    printf("enter the elements in the first array\n");
    for(i=0;i<a;i++)
    {
         printf("enter the %d element\n",i+1);
         scanf("%d",p+i);
    }
    printf("enter the elements in the second array\n");
    for(i=0;i<b;i++)
    {
        printf("enter the %d element\n",i+1);
        scanf("%d",q+i);
    }
    sort(p,a);sort(q,b);
    
    r= add(p,a,q,b);
    sort(r,tem);
    printf("the sorted and combined list without repetitions is\n");
    for(i=0;i<tem;i++)
    {
        printf("%d\n",*(r+i));
    }
    return 0;
}
void sort(int *p,int a)
{
    int i,j,temp;
    for(i=0;i<a;i++)
    {
        for(j=i;j<a;j++)
        {
            if(*(p+i)>*(p+j))
            {
                 temp=*(p+i);
                 *(p+i)=*(p+j);
                 *(p+j)=temp;
            }
        }
    }
}
int *add(int *p,int a,int *q,int b)
{
    int i,j,k;
    int *r;
    int z,count=a+b;/* initialized count as the total number of elements
                       in both including repetitions*/

    r=(int *) malloc(count*sizeof(int));

    for(j=0;j<a;j++)
    {
        for(k=0;k<=tem;k++)
        {
            if(k==tem&&tem!=0)
                break;
            if(*(r+k)!=*(p+j))
            {
                *(r+tem)=*(p+j);
                tem++;
            }
        }
    }
    for(j=0;j<b;j++)
    {
        for(k=0;k<tem;k++)
        {
            if(*(r+k)!=*(q+j))
                *(r+tem)=*(q+j);
            tem++;
        }/*at last tem will be equal to count.*/
    }
    return r;
}

Posted 13-Jun-15 8:37am

Member 11324568

Updated 20-Jul-18 9:52am

Frankie-C

v12

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Comments

Richard MacCutchan 14-Jun-15 3:09am


            if(*(r+k)!=*(p+j))
                *(r+tem)=*(p+j);

How do you expect anyone (even you in a few weeks) to understand such obfuscated statements? Use readable variable names and comments to make your code clear.

Member 11324568 14-Jun-15 7:07am

sir,i,j,k are the general variables used for running the loop , while p,q are the pointers to the first element of two arrays.I have used all the variables of a particular kind as continuous alphabets to avoid confusion.

[no name] 14-Jun-15 9:17am

Variables should have meaningful names otherwise nobody even you can understand the code. Why are you in this situation - think about it? Why would anyone waste valuable time looking at this puzzle? Rewrite it clearly and it may just work.

Member 11324568 14-Jun-15 9:20am

Alright ,i will use meaningful variables,try to help me find out the error here.

[no name] 14-Jun-15 9:22am

In the world I live in people debug their own code. That is all you are asking. Try harder.

Member 11324568 14-Jun-15 9:26am

I am new to programming and i am able to write algorithms but i'm making certain mistakes while converting it to code...i already wrote 2 versions of the code without arrays, but i'm just trying to learn my mistake here, so that i won't repeat them in the long run...thanks

Philippe Mori 14-Jun-15 8:32am

Please let the code formatted as C++ code. Stop removing the formatting. It is no hard to properly use this site so make some effort.

Andreas Gieriet 14-Jun-15 8:52am

Please *don't* revert the current formatting - the original formatting was so broken that no one can reasonably help.
Thanks
Andi

2 solutions

Solution 2

#include<stdio.h>
int main()
{
    int a[30],b[30];
    int n,k,i,j,p,c=0;
    printf("How many element in first array\n");
    scanf("%d",&n);
    printf("Enter elements");
    for(i=0;i<n;i++)
    {
        scanf("%d",&a[i]);
    }


     printf("How many element in sceond array\n");
    scanf("%d",&k);
    printf("Enter elements");
    for(i=0;i<k;i++)
    {
        scanf("%d",&b[i]);
    }
     printf("The new array is \n");
     for(i=n,j=0;i<(n+k);i++)
     {
         a[i]=b[j++];
     }

     for(i=0;i<(n+k);i++)
     {
         printf("%d ",a[i]);
     }
    for(i=0,p=0;i<(n+k);i++)
    {
        if(a[i]!=NULL)
        {

            for(j=i+1;j<(n+k);j++)
            {
                if(a[i]==a[j])
                {
                    a[j]=NULL;
                }
            }
            a[p++]=a[i];
            c++;
        }


    }
printf("\nAfter eliminate the dublicate elements,the new arry is : \n");
for(i=0;i<c;i++)
     {
         printf("%d ",a[i]);
     }

}

Posted 20-Jul-18 9:52am

Member 13920176

Comments

jeron1 20-Jul-18 16:04pm

Dumping code for a question over three years old, with no corresponding explanations is maybe not the best thing to do. What happens if I enter 80 for the number of elements?

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Philippe Mori · Accepted Answer · 2015-06-13T09:31:00

Solution 1

First of all, you should not SHOUT.

Then, you should explain what is your problem.

Anyway, the following line is probably wrong:

C++

if(*(p+i)==*(p+j))

You are comparing item from first array with item from the same array.

Also, it seems that when this line is executed, tem is not yet initialized to the desired value (but still 0):

C++

for(k=0;k<tem;k++)>

Given that, that loop is never executed. Same problem a few lines below. You are probably using the wrong variables at some places in those loops.

Without looking further and without even trying your program, it is clear that it will not work as intended.

Then, your program is far from optimal. You allocated r at 2 places. The one in main is useless.

Also, if you sort both array, you don't have to compare each item in each array but you can add the minimum item form the current location in each array and you won,t need to sort the result once more at the end.

Alternatively, it you know that original arrays don't have duplicated or you want to removed duplicate, you might make a big array and sort it once then remove duplicates either in place or into a new array.

Posted 13-Jun-15 9:31am

Philippe Mori

Comments

Member 11324568 14-Jun-15 7:24am

sir, code has been updated,yet it doesn't work, after i run the code and after i give all the details as input i get on the display. its not working...what to do now?

Philippe Mori 14-Jun-15 8:44am

It seems that you have only considered the first two points.

You should use a debugger to understand your own code although in this case, it is not that hard to figure out that the code is still incorrect. In particular tem is only incremented if it is not zero since loop only executed in that case!

By the way, write your code one funcion at a time. Start with 2 arrays already sorted and no duplicate and element in second arrays all greater than those in first one. Make appending works in that case, then add another case like unsorted array, then overlapping range and finally duplicates.

Member 11324568 14-Jun-15 9:21am

Yes sir ,the third method you told me to do is very efficient compared to what i had written,but i'm just curious to know what mistake i have made so that i can avoid that sort of mistake,and i'm just a beginner in c programming.

Andreas Gieriet 14-Jun-15 9:49am

Use qsort from stdlib.h instead of re-inventing sorting.
Don't use global variables in functions (like you use tem in the add function, etc.).
Try run the code with paper and pencil (or run it in the debugger...) to identify what control flow or data which is not as expected.
Cheers
Andi

Member 11324568 14-Jun-15 10:46am

thanks :) i didn't know about qsort..and i started watching videos on how to use debugger..

Andreas Gieriet 14-Jun-15 11:10am

For exercise and learn most, I suggest you walk through your code on paper and pencil to evaluate manually the control flow and the values of the variables. You will notice that naming is crucial. And you will see that using global variables within functions is heavily making life difficult (i.e. depends on the sequence of execution).
Cheers
Andi

Member 11324568 14-Jun-15 15:51pm

Is there any problem except memory utilization while using global variables ?

Member 11324568 14-Jun-15 15:52pm

Thanks a lot for your suggestions sir

Andreas Gieriet 14-Jun-15 16:45pm

You might digest this: Why is Global State so Evil?.
Cheers
Andi