Question

Is there any memory leak ?

    const char * pname = "NAME";
    char * temp = new char[strlen(Name) + 64];
    sprintf(temp,"%s", pname);

    delete [] temp; // is there any memory leaks because now length of temp is 4.

Answer 1

No there won’t be any memory leak. sprintf will only use the bytes of temp that it requires, BUT, all of the bytes initially created will remain allocated (even though some are unused).

The call to delete[] temp will then deallocate all the bytes originally allocated.

As others have pointed out though, do not free pname. You should only call delete and delete[] on pointers which were created with new and new[] respectively.

Additional information:

When you created temp, new[] allocated an array of contiguous bytes in memory PLUS an additional (small) space where it stores the information about the allocation (how large the allocation is, for instance). When you called delete[] it examined that information and found that strlen(Name)+64 bytes were allocated, and so it knows it has to deallocate all of them. The fact that you only used a small fraction of the allocated space does not make a difference.