I'm coding a program to use selection sort in C program using functions and arrays but I'm getting error as undefined reference to `swap'

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I'm coding a program to use selection sort in C program using functions and arrays but I'm getting error as undefined reference to swap

What I have tried:

C

#include <stdio.h>
#include <stdlib.h>
void sorting();
void swap(int,int);

int main()
{
    int array1[5];
    int i;
    int j;
    printf("enter your elements:\n");
    for(i=0;i<5;i++)
    {
        scanf("%d",&array1[i]);
    }
    sorting(array1);
 return 0;
}

void sorting( int *array2)
{

    int i=0;
    for (i=0;i<5;i++)
    {
        for (int j=i+1;j<5;j++)
          if(array2[i]>array2[j])
        {
            void swap(&array2[i],&array2[j]);
        }
    }

    void swap(int*a,int*b)
    {
        int temp;
        temp=*a;
         *a= *b;
        *b=temp;

    }
    printf("\n");
    printf("Array in sorted order is");
    for(int i=0;i<5;i++)
    {
        printf("%d ",array2[i]);
    }
}

Posted 26-Oct-21 22:43pm

Nithish Karthikeyan

Updated 27-Oct-21 1:22am

Dave Kreskowiak

v3

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Comments

CHill60 27-Oct-21 4:54am

Compare the declare void swap(int,int); to the implementation void swap(int*a,int*b)

Nithish Karthikeyan 27-Oct-21 5:05am

how do I do that?

Richard MacCutchan 27-Oct-21 5:26am

Change the definition at line 4 to:

void swap(int*, int*);

so it matches the actual function.

CHill60 27-Oct-21 6:17am

I meant "look at the difference" - in other words what are the differences between those two lines - Richard and OriginalGriff have told you how to fix it, but just look at those two lines! One has * in it and the other does not.

3 solutions

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OriginalGriff · Accepted Answer · 2021-10-26T23:40:00

Function prototypes such as

C++

void sorting();

and

C++

void swap(int,int);

must have an identical signature to the function when it is actually declared: if it doesn't, then the two do not "match up" and the prototyped function is technically not defined at all.
Compare the prototype definitions with the actually bodied versions:

C++

void sorting( int *array2)
{
...
}
void swap(int*a,int*b)
{
...
}

And you can see why they do not match.

In addition, C does not support "functions within functions" so you need to move the declaration of the swap function outside the body of the sorting function.

CPallini · Accepted Answer · 2021-10-27T00:49:00

Try

C

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

void sort(int array[], size_t len);
void swap(int * pa, int * pb);


enum { SIZE = 5 };

int main()
{
    int arr[SIZE];

    printf("enter your elements:\n");
    for(int i = 0; i < SIZE; ++i)
    {
       if (  scanf("%d",&arr[i]) != 1 )
        return -1;
    }

    sort(arr, SIZE);


    printf("sorted array:\n");

    for (int i = 0; i < SIZE; ++i)
    {
      printf("%d\n", arr[i]);
    }


 return 0;
}

void sort( int arr[], size_t len)
{
    for (int i=0; i <(len-1); ++i)
    {
        for (int j=i+1;j<len; ++j)
        {
            if( arr[i] > arr[j] )
            {
              swap(&arr[i],&arr[j]);
            }
        }
    }
}

void swap(int * pa,int *pb)
{
    int temp;
    temp=*pa;
    *pa= *pb;
    *pb=temp;
}

Patrice T · Accepted Answer · 2021-10-27T01:22:00

Quote:
I'm coding a program to use selection sort in C program using functions and arrays but I'm getting error as undefined reference to swap

Reason is that in C you can't define a function inside another function.

C++

#include <stdio.h>
#include <stdlib.h>
void sorting();
void swap(int,int);

int main()
{
    int array1[5];
    int i;
    int j;
    printf("enter your elements:\n");
    for(i=0;i<5;i++)
    {
        scanf("%d",&array1[i]);
    }
    sorting(array1);
 return 0;
}

void sorting( int *array2)
{

    int i=0;
    for (i=0;i<5;i++)
    {
        for (int j=i+1;j<5;j++)
          if(array2[i]>array2[j])
        {
            void swap(&array2[i],&array2[j]);
        }
    }

    printf("\n");
    printf("Array in sorted order is");
    for(int i=0;i<5;i++)
    {
        printf("%d ",array2[i]);
    }
}

void swap(int*a,int*b)
{
    int temp;
    temp=*a;
     *a= *b;
    *b=temp;

}

I'm coding a program to use selection sort in C program using functions and arrays but I'm getting error as undefined reference to `swap'

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I'm coding a program to use selection sort in C program using functions and arrays but I'm getting error as undefined reference to `swap'

3 solutions

Solution 1

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Solution 3

Add your solution here

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