Question

Hello can someone help me figure this out for my revision using C Programming. thanks!

Given the following function prototype: void trimPositive(int* *arr, int *size) ;

write the corresponding function definition such that: given any (dynamically allocated) array of ints and its size via the arr and size parameters, the result of your function is that:

a) the int* array argument points to a new (dynamically allocated) array that is completely full, and whose values are exactly the positive values of the array that it pointed to before the call.

b) the int size argument has been set to the number of elements in this newly created array.

Note: Your function must be free of memory leaks.

Answer 1

// C program to create and test function trimPositive
#include <stdio.h>
#include <stdlib.h>

// function that will remove all negative elements from dynamic array arr so that arr contains only positive values
// of the array that it pointed.
void trimPositive(int* *arr, int *size)
{
   int i,j, curr_size = *(size); // set curr_size to value in size
   // loop over the array
   for(i=0;i<curr_size;)
   {
       // if ith element is negative
       if(*(arr[i]) < 0)
       {
           // shift the contents of the array to left by 1 position
           for(j=i;j<curr_size-1;j++)
               *(arr[j]) = *(arr[j+1]);
           curr_size--; // decrement current size
       }else // if positive, then go to the next element
           i++;
   }

   // create and allocate a temporary array to store the updated array of updated size curr_size
   int **temp = (int**)(malloc)(sizeof(int*)*(curr_size));
   // loop to copy the elements
   for(i=0;i<curr_size;i++)
   {
       temp[i] = (int*)(malloc)(sizeof(int));
       *(temp[i]) = *(arr[i]);
   }

   // loop to free the memory held by arr
   for(i=0;i<*(size);i++)
       free(arr[i]);
   free(arr);
   // update the size
   *(size) = curr_size;
   // allocate memory for new arr
   arr = (int**)(malloc)(sizeof(int*)*(*size));
   // copy the elements to arr
   for(i=0;i<*(size);i++)
   {
       arr[i] = (int*)malloc(sizeof(int));
       arr[i] = temp[i];
   }
}

int main(void) {
  
   // test the function
   int size = 10, i;
   // create an array fo size 10
   int **arr = (int**)(malloc)(sizeof(int*)*(size));

   // allocate memory for each element
   for(i=0;i<size;i++)
       arr[i] = (int*)malloc(sizeof(int));
   // set elements of arr
   *(arr[0]) = 5;
   *(arr[1]) = 10;
   *(arr[2]) = -5;
   *(arr[3]) = 12;
   *(arr[4]) = -2;
   *(arr[5]) = -7;
   *(arr[6]) = 5;
   *(arr[7]) = 6;
   *(arr[8]) = 14;
   *(arr[9]) = 5;
   //display the original array
   printf("\nOriginal array : \n");
   for(i=0;i<size;i++)
   {
       printf("%d ",*(arr[i]));
   }
   printf("\nAfter Trim Positive Array:\n");
   // call the function to remove the negative values
   trimPositive(arr, &size);
   // display the array after function call
   for(i=0;i<size;i++)
   {
       printf("%d ",*(arr[i]));
   }
  
return 0;
}

//end of program

Output: