Question

The code below move the an element to top of an array

for ( i = j; i > 0; i-- ) {
  myBlk *tmp = blks[i];
  blks[i] = blks[i-1];
  blks[i-1] = tmp;
  delete tmp;
}

as the execution reaches delete tmp, I get:

*** glibc detected *** double free or corruption (out): 0x00007fffd556ad10 ***

If I remove that statement, there is no problem. But I don’t want memory to leak…

Answer 1

Promoting comment to answer.

It seems that you are confusing a memory allocation with a pointer copy. In your loop, you are not doing any memory allocation. You are just copying a pointer – which does not allocate memory.

So you should get rid of the delete:

for ( i = j; i > 0; i-- ) {
  myBlk *tmp = blks[i];
  blks[i] = blks[i-1];
  blks[i-1] = tmp;
}

delete is only called when there is memory allocation – which you have none of. (none inside the loop at least)