Question

Send an element from 2d array to a function using pointer to pointer. c++

I am having an issue with being able to send specific elements to the swap function.

#include <iostream>
using namespace std;

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

void selSort(int **arr, int d){
   for(int i =0; i<d-1; i++){
       int min = *(*arr+i);
       int minin = i;
       for(int j =i+1; j<d; j++){
           if(*(*arr+j) < min){
               min = *(*arr+j);
               minin = j;
           }
           swap(*&(arr+i),*&(arr+minin));
       }
   }

}

int main() {
   int array[2][2] = {4,3,2,1},
       *ptr = &array[0][0],
       **pptr = &ptr;
   int size = sizeof(array)/sizeof(int);

   for(int i =0; i<size; i++){
           cout <<*(*pptr+i)<<endl;
       }

   selSort(pptr, size);

   for(int i =0; i<size; i++){
           cout <<*(*pptr+i)<<endl;
       }

   return 0;
}

Answer 1

#include <iostream>
using namespace std;

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

void selSort(int **arr, int d){
for(int i =0; i<d-1; i++){
int min = *(*arr+i);
int minin = i;
for(int j =i+1; j<d; j++){
if(*(*arr+j) < min){
min = *(*arr+j);
minin = j;
}
swap(*(*arr+i),*(*arr+minin));

// *arr derference value and add to min and then *(*arr+i) is the address which is passed
}
}

}

int main() {
int array[2][2] = {4,3,2,1},
*ptr = &array[0][0],
**pptr = &ptr;
int size = sizeof(array)/sizeof(int);

   cout<<"Before Sorting: \n"; // msg you can also delete it if want
for(int i =0; i<size; i++){
cout <<*(*pptr+i)<<endl;
}

selSort(pptr, size);
   cout <<"After Sorting: \n";
for(int i =0; i<size; i++){
cout <<*(*pptr+i)<<endl;
}

return 0;
}

/* OUTPUT */