CODEWITHSUNDEEP
c
Jackson Arms
Jackson Arms

Reputation: 3

memcpy() between two different pointers

Using memcpy(), I want to copy part of an array to another one where the source array is a double-pointer array. Is there a workaround to implement such a copying process without changing the double pointer?

int **p;
p= malloc(sizeof(int *));
p= malloc(5 * sizeof(int));

int *arr;
arr= malloc(5 * sizeof(int));

for(i = 0; i < 5; i++){
  p[i] = 1;
}

memcpy(arr, (2+p) , 3*sizeof(int)); // I want to start copying 3 elements starting from the third position of the src.

Upvotes: 0

Views: 1627

Answers (1)

ameyCU
ameyCU

Reputation: 16607

Here is a simple example to do that -

int main(void){
   int **p;
   int *arr,i;
   p= malloc(sizeof(int *));        // allocate memory for one int *
   p[0]=malloc(5*sizeof(int));      // allocate memory to int *
   for(i = 0; i < 5; i++){
        p[0][i] = i+1;             // assign values
     }      
  arr= malloc(5 * sizeof(int));        // allocate memory to arr
  memcpy(arr,&p[0][2],3*sizeof(int));  // copy last 3 elements to arr

  for( i=0;i<3;i++){              
     printf("%d",arr[i]);              // print arr
   }
  free(p[0]);
  free(p);
  free(arr);

}

Output

Upvotes: 1

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